Nico di Angelo

"Just who I am... Easy for you to say. You're everybody's golden boy, the son of Jupiter. The only person who ever accepted me was Bianca, and she died! I didn't choose any of this. My father, my feelings..."

- Nico di Angelo to Jason Grace

Nico di Angelo is a fourteen year old Greek demigod son of Hades and the mortal Maria di Angelo. He is also the younger brother of the late Bianca di Angelo and the half brother of Hazel Levesque. He is known in the Underworld as the "Ghost King" after taking the title from King Minos.

History
Nico di Angelo was born sometime in the early 1930's in Venice, Italy before Hades and his brothers took an oath to have no more children. Since Nico was born in Italy and his mother was Italian, he can speak fluent Italian. He had an older sister named Bianca di Angelo. Around the age of six, Nico visited Diocletian's Palace in Split, Croatia. At some point near the beginning of World War II, Nico and his family left Italy for the United States, where they stayed at a fancy hotel. Their mother, Maria, died when Zeus struck the hotel they were staying in with lightning in order to kill the siblings. However, they were protected by Hades as he erected a wall of black energy to shield them from Zeus. However, Hades was not able to protect their mother in time. Both of them were brought to the Lotus Hotel and Casino by the Fury Alecto, who was disguised as a lawyer for their own safety. Alecto was also instructed by Hades to bathe them in the River Lethe to wipe their memories. Sometime before being placed in the Lotus Hotel, Bianca and Nico lived in Washington D.C. for a time.

After what the siblings thought was a month in the Lotus Hotel (which was actually approximately seventy years), they were taken out by a lawyer. This lawyer however was a different lawyer than the one who brought them in. Hades' intention for taking them from the Lotus Hotel was because he wanted one of them to be the child of the Prophecy and not the "idiot" son of Poseidon, referring to Percy Jackson. They were brought to a military school in Maine, paid for by Hades using what they thought to be a trust fund left to them by their parents.

The Titan's Curse
Nico first appears with his sister, in a military school called Westover Hall, in Bar Harbor, Maine. Bianca and Nico were almost kidnapped by a manticore named Dr. Thorn. Thalia Grace, Grover Underwood, Percy, and Annabeth Chase attempted to save them, but it is the Hunters of Artemis who come to the rescue. The siblings were sought out by Grover, who believed them to be two very powerful unknown half-bloods. Nico looks to be about ten and seems to be very interested in Mythomagic, a card game about Greek mythology. But when 12 year-old Bianca accepts Artemis' proposal to become a Hunter, Nico gets angry at her for abandoning him. When Bianca goes on a quest to find Annabeth, Percy finds Nico eavesdropping on Bianca and Zoë Nightshade, and Nico successfully convinces Percy (for whom Nico had developed secret romantic feelings for) to promise to keep his sister safe on the quest. He doesn't appear again until after Percy returned from the quest, where Percy explains to him that Bianca died to save the others on the quest. He immediately turns on Percy, telling him he hates him, and reminding him of the promise he made to keep Bianca safe. Percy tries to comfort him, and Nico claims he can sense her soul being judged. When the last four Skeleton Warriors appear in the camp, Nico, not wanting them to hurt Percy, tells them to "Go away!" and they are swallowed by a fissure in the ground that Nico creates by accident. Nico is last seen running into the woods at night. Percy then realizes that Nico is a son of Hades after slipping over on and finding the god figurine that Bianca told Percy to give Nico if she died. It was the only one he didn't have (in his Mythomagic collection). The figurine was Hades, Lord of the Dead. He left the Camp through Daedalus'  Labyrinth, where he would meet Minos. It is later revealed that another major reason he ran away that day was love--his romantic feelings for Percy that terrified Nico, who could not initially come to terms with them.

The Battle of the Labyrinth
Nico is first seen through the Iris message that Bianca sent to Percy. He has honed his powers as the son of Hades with help from the ghost King Minos, who had been training him. He tried to summon Bianca's ghost many times, but failed. Frustrated, he seeks to make a deal with his father by trading "a soul for a soul." Percy thinks that Nico is after him, but Nico is after somebody else.

Nico decides to find the soul of someone who cheated death and trade it for Bianca's. Later, he meets Percy, Annabeth, Tyson, and Grover at the Triple G Ranch. He'd entered the ranch to discuss finding the soul he needed with Geryon. Angered, he threatens them, but is stopped by Geryon. He still blames Percy for Bianca's death, and tells him so. He is then tied up by Geryon to be sold to the Titan Army. When Percy offers a deal to Geryon to save him, Nico shouts that he does not want to be saved by Percy.

Percy still saves Nico, and convinces him to try and summon Bianca's spirit again. It works, however, Bianca tells Nico not to be angry at Percy or hold grudges, because that is the fatal flaw of the children of Hades. She says to stop blaming Percy because it is really she that Nico is angry at for abandoning him. She also gives a warning about Kronos sensing Nico, and then she disappears.

He stays at the Triple G Ranch while the others leave. Nico is tricked by Minos into going back into the maze to save Percy, but is captured by two dracanae of Kronos'. In the battle at Daedalus' Workshop, Nico opens a fissure in the ground, sending Minos back to the underworld. He tells Percy that only the dead accept him, and they only do so out of fear.

He escapes with Percy, Annabeth, and Rachel Elizabeth Dare, who have to go back into the Labyrinth to find Grover and Tyson. Along the way, they see Kronos (in the form of Luke Castellan), and Nico, in a desperate attempt to save everyone, shows his true powers, by conjuring a wall of black stone that stops Kronos from following them back in to the Labyrinth but also making it known to Kronos that he is a son of Hades.

When they found Grover and Tyson, they also found the long-lost god Pan, and Nico notices that he is the only one that Pan doesn't talk to.

During the battle at Camp Half Blood, Nico summons many undead warriors to fight, and stop some rogue dracanae from reaching the cabins of the gods. The effort nearly kills him and he collapses on the ground, with his clothes smoking, at the end of the battle. Percy finds him and helps him by giving him nectar. He releases Daedalus' soul after that, who offers his soul for ransom, but Nico decides Bianca should stay where she is.

He feels out of place at Camp Half-Blood, and refuses to eat with the other demigods or join the singalong at the campfire. Nico summons Bianca's spirit one last time to say goodbye. He tells Percy that he will leave Camp Half-Blood because he feels that he doesn't belong there like his father doesn't belong on Olympus. Before he leaves, Percy gives him the small Hades statue that Bianca had given him before she died.

He appears again at the very end on Percy's birthday at his apartment, and offers a way to defeat Kronos, but is distracted by Percy's blue birthday cake (assuming he's probably never had a birthday party in his life), and Percy offers him some, and they both go inside to talk about Nico's secret plan to beat Kronos.

The Sword of Hades
Nico is one of the three demigods along with Thalia and Percy who are summoned by his step-mother Persephone to find the Sword of Hades. Percy thinks it's a bad idea but Nico is hoping to achieve recognition from his father Hades. He tells Thalia and Percy why they need to go on the quest. To Percy's irritation, he comes up with logical reasons. His knowledge of the Underworld and its occupants helps them complete their quest. He remains in the Underworld afterward to discuss the upcoming Titan War with his father. Before his friends leave, he reminds Percy of his idea to defeat the Titans.

The Last Olympian
Nico's theory to gain an edge over the Titans is finally revealed: it is to make Percy invincible by having him bathe in the River Styx, similar to the myth of Achilles. It is shown that after Bianca died, Hades believes that he has no competent child, repeatedly mentioning that Bianca could do a better job at fulfilling their father's demands. At some point earlier, Nico began preparing for his plan, and did some research on Luke's past, and had found May Castellan, his mother.

Later on, Nico is once more searching for information about his mother and childhood, a quest which brought him to  Mount Othrys. Nico is first seen there in Percy's dream, using a chance to eavesdrop on the Titans Hyperion and Krios, as well as the imprisoned Atlas. It is later confirmed that this was true. Shortly after Beckendorf sacrifices his life to destroy Kronos's ship, Nico speaks to his ghost, and learns that Beckendorf will go to Elysium. Nico also heard the lines of the Great Prophecy, presumably from another ghost, or Hades himself.

Later on, Nico arrives at Camp Half-Blood by shadow-travel, which initially terrifies Juniper and Leneus, and he briefly discusses Grover's disappearance with them, after which he encounters Percy. Nico is finally able to persuade him to go through with their plan, and both of them and Mrs. O'Leary shadow-travel to Luke's old house, and meet Mrs. Castellan. Afterwards, they briefly encounter the goddess Hestia, who greets them warmly and offers them food.

Soon after, the three enter the Underworld, where Nico, who was tricking Percy all along, has the Furies carry them to Hades' Palace. It is revealed, that in order to gain information about his past and his mother, Nico had to bring Percy to Hades in exchange, though Nico had no ill intentions, and only did it after making Hades promise not to harm his friend. His father reveals that the lawyer who removed Nico and Bianca from the Lotus Hotel and Casino was the Fury, Alecto, in disguise, but refuses to give him details on his mother's death. After Hades still imprisons Percy in his dungeons, Nico helps him break out, apologizes, and still follows through with his initial plan of having Percy bathe in the Styx and gain the Curse of Achilles.

Later, Nico attempts to summon the ghost of his mother, but Bianca's ghost appears and tells him not to. He sees the scene of their mother's death in which Zeus blasted the hotel she, Hades, and the children were in to pieces. Hades, who realized what was happening too late, only managed to save Nico and Bianca. He then orders Alecto to wipe the memories of the children in the Lethe, including their mother's death.

By viewing this scene, Nico finds out who his mother is and, in the end, is able to convince his father Hades to help the campers in battle.

Nico is the first to join the Battle of Manhattan, and fearlessly yells out a challenge to Kronos himself. Nico is soon joined by Hades himself, and they both summon wave after wave of the undead soldiers, who confront, and eventually overwhelm Kronos' forces. After the Titan Lord is defeated, Nico accompanies his father to Olympus, and sits at his father's feet when Percy and his friends are receiving gifts from the Olympians. Apparently, Nico, through his unwavering loyalty and bravery in battle, has finally gained his father's pride, as Hades pats Nico on the shoulder, and, according to Percy, this is "the happiest he's ever seen him." Since Hades is now accepted on Olympus, and Nico is accepted at Camp Half-Blood, Rachel is finally able to break Hades's curse on the Oracle, and become the next Oracle of Delphi herself. Apparently, almost all campers are in awe of Nico's fighting in Battle of Manhattan, as "even the Ares kids considered him cool." Nico is last seen when he orders undead workers to build the Hades cabin, made up of solid black obsidian walls with a skull over the door. There are torches inside that blaze with burning green fire that will never extinguish.

Between the Series
As revealed in The Son of Neptune, in the September following The Battle of Manhattan, after Thanatos had been captured, and the dead were returning to the world anyway, Nico had gone to the Underworld in hopes of rescuing his sister Bianca, but was unable to do so, because she decided to be reborn and thus couldn't be brought back to life. Instead, Nico found his half sister Hazel Levesque in the Fields of Asphodel, and felt that she deserved another chance at being a hero (Gaea said that he had selfish reasons for doing this, but it is unknown if he had any or for what selfish reasons did he do it for). Hades gives Nico directions on how to find Camp Jupiter, explains why the Olympians have kept both camps separated for centuries, and forbids him of telling anybody about it, as the time isn't right. As stated by Dakota, Nico took Hazel directly to Camp Jupiter and demanded Reyna and Jason to take her in.

The Lost Hero
Nico is mentioned by Annabeth to be searching for Percy along with Tyson, Grover, and the Hunters of Artemis, but otherwise doesn't appear. It's to be assumed that he doesn't stay at Camp Half-Blood much, as Annabeth said he "sometimes" shows up, which could be due to his double duty at Camp Jupiter as Ambassador of Pluto.

The Son of Neptune
Nico meets Percy at Camp Jupiter, where he is visiting his half-sister, Hazel Levesque. When they meet, Nico is shocked but easily regains control over it. He poses as a son and ambassador of Pluto, and even though most of the campers see him as harmless, Hazel knows that Nico is more dangerous than Reyna, Octavian, and maybe even Jason Grace. Nico tells Percy about the return and defeat of Kronos (referring to him as Saturn), and about Gaea. Nico later tells Hazel, after Percy leaves with Frank Zhang, that he knows Percy, but Percy must regain his memories by himself, since he needs to find his own way at the camp and Nico can't interfere. It is later revealed that Nico was forbidden to do so by Hades himself, since the time wasn't right yet. Hazel and Nico had a time to talk when he mentioned about Bianca he's sister who died, he mentioned that he missed his sister and he wanted to see it.

Later, Nico is shown to be observing the War Games from afar using a pair of binoculars. When Mars appears, Mars glares at Nico while mentioning that people will no longer be held to death, implying that he knows about him saving Hazel's spirit. Nico is later shown in the meeting, where he is present as a Senator in a black toga, and the Ambassador of Pluto. Nico supports Frank, Percy, and Hazel by telling them about the first Gigantomachy, Alcyoneus, and Thanatos, all of which makes Reyna suspicious. However, Nico doesn't say anything when Octavian protests and wins the argument. Nico leaves Camp Jupiter before Hazel to see if he can locate the Doors of Death from inside the Underworld. During his search, Nico (believing he could go anywhere in the Underworld) comes too close to Tartarus and gets pulled in by the dark gravity the pit generates (similar to a black hole). Though he fought back, Nico was overwhelmed and defeated by the sheer number of Gaea's forces down in Tartarus.

Nico is later shown in one of Hazel's flashback blackouts. He finds Hazel in the Fields of Asphodel and brings her back to the mortal world to give her another chance at life.

During the quest for the god Thanatos, Gaea mentions that when she used Hazel, she was at least honest about it, unlike Nico who she claims was lying to Hazel. Gaea also says that Hazel should be happy that she captured him, and that he is now somewhere in Rome. Gaea later tells this to Percy and he promises that they will find out what happened to him.

When they free Thanatos, Hazel asks if Nico is alive. While Thanatos doesn't say if he is alive or dead, he does say they will find the answers in Rome. Later after Percy regains his memory, he calls Mrs. O'Leary, much to Hazel's surprise. He tells her that Nico could tell her the story before realizing what he had said. On the way back to Camp Jupiter, Percy fully regains his memory, and is quite angry at Nico for not telling him about his past. After Polybotes is defeated, Hazel mentions that Pluto is turning a blind eye to her to let her live and she feels that he wants her to find Nico.

The Mark of Athena
Even though Nico is a son of Hades, he barely survived the trip into Tartarus, and almost went insane. Gaea's forces went down there and overwhelmed him almost instantly, since they are extremely powerful in Tartarus. Afterwards, in order to lure the seven heroes into a trap, Gaea had Nico transported out of Tartarus through the House of Hades (an underground temple in Greece), and taken to Rome, where her twin giant sons Otis and Ephialtes sealed him in a bronze jar, similar to how Ares was once held captive by the two giants.

Percy sees him in his dream, imprisoned in the jar in a coma-like state. He had marked three scratches on the wall of the jar, one for each pomegranate seed he had eaten. The seeds are a last resort food, which only children of Hades or Pluto can eat. Hazel explains that the seeds last for up to one day and put him in a death like state so that he doesn't use up all his air, something Hazel calls a death trance. Percy, Jason and Piper go to Nico's rescue, which they know is a trap set up by the earth goddess Gaea. Prior to discovering the twin giants Ephialtes and Otis, who were holding Nico captive, the trio came across an abandoned nymphaeum, whose nymphs they set free.

After making it to Rome, Hazel, Frank, and Leo try to find Nico, which leads them to the Pantheon, but they are lead into a trap, and are almost killed by eidolons. After defeating them, Leo realizes that Hazel was trying to track Nico by using his sword as a beacon, which they find lying in the workshop.

Meanwhile, during Percy and Jason's battle against Otis and Ephialtes, the jar Nico was held in breaks open and Piper McLean manages to pull the incredibly weakened Nico to safety. Later back on the ship, Nico tells them how he was captured and what he now knows about the Doors of Death. Nico had found out that the Doors of Death have two sides: one in the mortal world and one in Tartarus. The mortal side of the portal is in Greece, in a place called the House of Hades and it is guarded heavily by Gaea's forces. Nico then says that the other side of the doors are in Tartarus, a place not even the gods go and that is why Hades has not been able to close the doors. Not even the god of death, Thanatos, would go near Tartarus.

Leo guesses that the seven heroes will have to go to Tartarus and close that side of the portal, but Nico says that it would be impossible, not even they would stand a chance down there. Percy then says that they can set sail for the House of Hades, defeat Gaea's forces, and close the doors on the mortal side. Nico however says that it is not that easy and that the Doors of Death have to be controlled on both sides to be closed, as they are like a double seal. He says that maybe all eight of them working together could defeat Gaea's forces on the mortal side, but that they would need a team fighting simultaneously on the Tartarus side; a team powerful enough to defeat a legion of monsters in their home territory.

In Arachne's lair, when Percy tries to save Annabeth from falling into Tartarus, Percy catches hold of a ledge just in time. Nico tries to help, but he is out of reach. Annabeth tells Percy to let go, but Percy says that he will not lose her again. Percy tells Nico that they will see the rest of the seven and Nico on the other side, and makes him promise to lead the others there. Nico promises and Percy lets go, allowing the dark gravity of Tartarus to pull him and Annabeth in. During a meeting on the Argo II, Nico admits that Percy is the most powerful demigod he has ever met and with Annabeth there with him, he is sure they will be safe. He assures Leo that both Percy and Annabeth are still alive.

The House of Hades
The Argo II is being attacked by numina montanums, or mountain gods, who are attacking with boulders. As they attack, a boulder hits the mast, causing it to collapse on top of Nico. Hazel Levesque runs to help Nico up from the debris, but he tells her he is fine. When Leo complains that masts don't grow on trees, Nico corrects him by saying that masts are made from trees, which only serves to annoy Leo further. Leo is forced to retreat again and the three try to think of an alternate way past the Earth gods.

Nico explains that they don't like them because children of Hades or Pluto get under their skin. When it is suggested that they take the Argo II around the mountains over the water, Nico explains that going that way is longer and without their sea expert, Percy, it might be too dangerous. Nico also complains that he is to weak to simply Shadow Travel the ship across the mountains. While coming up with ideas, Hazel tries to think of a way to help, not wanting her only contribution to be removing a dangerous obstacle Nico had told her was in the House of Hades. When Hazel prays to her father for help, Arion appears, running towards them and that they should land to meet him. Leo replies that they should stay away from landing on the ground, but he will get Hazel as low as possible. Nico asks who Arion is and is told by Leo that he is Hazel's horse.

While going to retrieve the Diocletians scepter in Split, Croatia they meet the god Cupid. Cupid continues to pick on Nico for not coming to term with his true feelings. Cupid forces Nico to admit that he had feelings for Percy, in front of Jason Grace. Jason attempts to comfort him and promises to keep it a secret, but he continues to brush Jason away.

Later Nico confronts Jason about leaving the palace of the Lord of the South Wind. Jason again attempts to comfort Nico about what happened previously, saying that the others won't judge him. Nico becomes angry and claims that as a son of Hades he would never be accepted anywhere and always judged. In his anger, the ground opens up and Nico seems to shimmer with ghostly light. Jason then challenges him by saying that he should take a risk and believe that Jason really is his friend. As the scene reaches a climax, Nico tells Jason that "I'm going to honor my promise. I'll take you to Epirus. I'll help you close the Doors of Death. Then that's it. I'm leaving- forever." The son of Hades then disappears back into the shadows.

At Epirus, Nico leads the group into the underground temple. He works with Frank Zhang to summon and control the dead legion against the group of monsters after the temple collapses and separates the group. The group reunites, and finds Percy and Annabeth Chase purged from the Doors of Death. They work together to fight Clytius and when he is defeated, Nico and Hazel shadow-travel the group to safety as the temple caves in.

Nico and the group meet with and share a meal with Reyna Avila Ramírez-Arellano before Nico leaves to rest due to his future plans to Shadow Travel.

At the end of the book, Nico ties the statue up with rope to be able to it and Percy comes to thank him for keeping his promise. Nico cuts him off and tells him to give him space. He then shadow travels with Reyna and Coach Hedge to get the Athena Parthenos to Camp Half-Blood to help Reyna stop the impending civil war between both camps.

Personality
In The Titan's Curse, Nico is ten years old and enjoys playing with his Mythomagic cards that none of the others truly seem to understand. He is clueless and very inquisitive: he is curious and questioning and likes Percy a lot like a big brother (though it is later revealed that he has secret romantic feelings for him), and begins annoying Percy with his ceaseless questions, especially when he asks if Annabeth Chase was his girlfriend, which makes Percy consider "stuffing him in a meat flavored sack and throwing him to the wolves." He is excited about finding out that he is a demigod (immediate response: "Cool!"), and compares monsters to Mythomagic creatures. He feels abandoned when his sister Bianca, who practically acts as his parent, becomes a Hunter of Artemis. When she goes on a quest, Nico makes Percy promise to protect her. After her death, he develops a long-lasting grudge toward Percy for letting her die. Once he realizes that he is a son of Hades, he casts away his childhood interests and runs off on his own.

In The Battle of the Labyrinth, he becomes grim and solitary and definitely a more powerful character, saying that "only the dead respect me...and only out of fear." His attitude change may have happened partially because of Bianca's death and partially because of Minos' manipulations. He believes that he will never be accepted by the living and does not belong at Camp Half-Blood in comparison of his father feeling out of place on Olympus. He is also shown to be somewhat vengeful, as he wanted revenge for Bianca's death, something he blamed Percy for. However, Nico forgives Percy after Bianca's ghost tells him that it wasn't his fault that she died. He also accepts the small figurine of Hades that Bianca wanted him to have.

In the same book, he is shown to be very naive and gullible, being able to believe that Minos was actually helping him bring Bianca back from the dead. Nico cares much about his sister and the constant attempts to bring her back show that he would not give up without trying. Nico is shown to be very loyal to the Olympians, as he could have easily joined Kronos and the Titans, but chose to fight on the Olympians' side.

In The Last Olympian, he is quite sincere in wanting to help Percy with the prophecy and the war. However, Nico can be somewhat untrustworthy at times. This is shown when he tricked Percy into coming to the Underworld so he could gain answers about his mother, but Nico wasn't planning on Percy becoming imprisoned. By standing up to both Kronos and Hades, he is shown to be that he is very brave and bold. He likes being on his own, not really wanting help from anyone. He keeps to himself a lot and is pretty secretive, which causes plenty of problems throughout the series. Nico wants to help Percy, and was very miserable at the thought that Percy did not trust him after his dad tricked him as well, by the end they were back to a brotherly relationship. Nico is later proven wrong in the belief he will not be accepted by the living. After the war is over, all the campers of Camp Half-Blood welcome Nico cheerfully: as Percy puts it, "Hey, show up with an army of undead warriors to save the day, and suddenly you're everyone's best friend." This helps lift Hades's curse from the Oracle.

In spite of Nico pretending not to know Percy in The Son of Neptune, he spoke very highly of him to Hazel, telling her that he is dangerous to his enemies and a valuable ally to his friends. Nico's relationship with Percy also shows how much he's grown and matured throughout the series. Nico is very caring to Hazel Levesque, his half sister, and tries to help her as much as he can. His helping her sort of parallels with how Percy helped him in several cases. This shows that he loves his family, even his half-siblings. Unfortunately, after returning from Tartarus in The Mark of Athena, Nico is very different. He turns more inward and withdrawn, with his eyes becoming somewhat glassy like something in him broke permanently. Percy compares him to pictures of prisoners of war, which he notes Nico kind of was. Hazels states in The House of Hades that Nico has become more reclusive and morose, preferring to stay on top of the ship's mast, in solitude. Nico becomes much more easily angered, defensive and takes to making creepy and humorless smiles. Nico, however, has happily smiled on two occasions: in The Last Olympian, right after he helps Hades defeat Kronos' army and gains his father's respect, and in The House of Hades, after he and Frank defeat Gaea's monsters at the Necromanteion.

Nico can be extremely dangerous as he is a son of the Big Three. He is very unpredictable, and due to his sister's death can be somewhat mentally unstable as demonstrated in The Battle of the Labyrinth. He has a short temper, just like Percy and Thalia. When Jason causes him to lose his temper in The House of Hades, Nico's fury was so intense, that it even scared Jason, who felt that a furious Nico was "more than he could handle." The only time Nico is ever shown to be terrified, is in The House of Hades, when he was forced to face Cupid, implying that Nico's greatest fear is exposing his homosexuality. Even though Nico seems to dislike being touched, he is shown to be very affectionate towards Hazel, having kissed her twice.

In The House of Hades, Cupid forces Nico to admit that he is homosexual, with romantic feelings for Percy, something that he has tried to hide for years, but he later refers to himself as "…impressionable."

Fatal Flaw
"Holding grudges has always been the fatal flaw of children of Hades."

- Bianca to Nico

Nico di Angelo's fatal flaw is holding grudges, as Bianca's ghost tells him. In his case, it can lead to not wanting help or not asking to be saved in deadly situations because he doesn't like someone. Examples are his not wanting to be helped by Percy, even when Geryon was going to sell him to the Titans and not wanting to go back in the Labyrinth with them. Bianca shares this with him, as she also had the same fatal flaw in life, although this didn't lead to her death. Bianca also says that holding grudges is the fatal flaw of Hades' demigod children. In the fifth book, Nico tells his father, Hades, that he is holding a grudge that could end up killing the Olympians and the campers. Ever since The Last Olympian, Nico hasn't demonstrated this flaw any more, implying that he has learned from his previous experiences, and tends to avoid holding grudges. However, this flaw resurfaces slightly in The House of Hades when Nico, coerced by Cupid, admits to Jason that he had feelings for Percy, and yet still clearly bears some resentment toward Annabeth, and an unwillingness to accept that he will most likely not end up with Percy, despite the fact that he claims to Jason that he has, "…moved on."

Appearance
He is said to have black hair that always looks like he just got out of bed (messy and shaggy), olive skin. By The Battle of the Labyrinth, his skin has paled to white, and he takes to wearing black clothing, a Stygian Iron sword and a silver skull ring (by the end of the book). By the time he meets Hazel Levesque, she describes his fingers as ghostly white, like their fathers', and dark eyes. It was stated by Percy that Nico has his mother's eyes, but it has also been said that he has the wild glint of a madman in them, just like his father.

By the end of The Battle of the Labyrinth, he has a silver skull ring which is said to belong to his father (as stated by Hazel), and he has a Stygian Iron sword always by his side in his chain belt. He is also mentioned on several occasions wearing an aviator's jacket, most likely because he was originally from WWII. Nico wears a black trench coat when he attempts to bring back Bianca, as shown in one of Hazel's blackouts. In The Last Olympian, Nico wears black battle armor with a skull-shaped helmet. In The Son of Neptune, Nico is seen wearing a black toga when Percy goes to talk to the senators (the reason being that togas are only worn on special occasions, like meetings). Nico always wears his Stygian Iron sword on his side in his chain belt. According to Hazel, when upset, Nico's face would "become as dark as Tartarus." In The Mark of Athena, Nico is much weaker, thinner and even paler than usual, while his eyes are described as "looking like shattered glass", due to his ineffable experience in Tartarus.

Days later, in The House of Hades, Nico has begun to recover and re-gain his strength, but is still described as "painfully thin," with his black shirt and jeans hanging loosely from his "skeletal frame". His dark hair is longer and frames his face. However, the area around his sunken eyes is very dark, while his complexion is even more pale than before, "a sickly greenish-white, like the color of tree sap." Being a demigod from another era, Nico radiates "a kind of old energy - a melancholy that came from knowing he didn't belong in the modern world."

Jason comments that since getting out of Tartarus, Nico "had slept little and eaten even less." Seeing Nico casually eat a grape, he thinks that that will be his food for the day. Later, Jason is surprised then Nico actually has visible muscles when he takes off his jacket. When Jason infuriates him, the ground opens up and Nico "glows with ghostly light." Even Jason admits to being afraid of the son of Hades.

Abilities

 * ADHD: Like most demigods, Nico possesses inborn supernatural battle reflexes and senses that he uses to analyze the fighting style of his opponent.


 * Dyslexia: Nico's brain is "hard-wired" for divine Ancient Greek instead of modern languages.


 * Fighting skills: Initially, Nico shows more skill with his powers than his fighting skills. However, this might have been due to his lack of formal combat training at camp. In The Demigod Files, he did show decent combat skills when he was able to keep up with Percy and Thalia when they fought a group of Keres. Not only did Nico emerge unscathed from the battle, but he easily defeated the Keres he fought. Later, he even fought the Titan Iapetus alongside Percy and Thalia (but he was quickly incapacitated). In The Last Olympian, Nico fights in the Battle of Manhattan, and emerges unscathed, implying excellent fighting skills. In The Son of Neptune, Hazel mentions being impressed the first time she saw him fight, suggesting that he honed his skills between the two series, possibly during his stays at either Camp Half-Blood or Camp Jupiter. Nico was even able to fight Gaea's army in Tartarus itself, though he was overwhelmed by their sheer numbers. In the House of Hades, Nico fights the army with only one hand, and then emerges unscathed after the battle is won, implying excellent swordsmanship.


 * Mythomagic: Nico's knowledge of the game is superb, as he had the rare Africanus Extreme expansion deck, and remembers each figure, as well as the number of attack and defense moves of each. Thus, he was able to identify Dionysus, a Manticore and even a Katoblepone.


 * Ancient Greek: In The Battle of the Labyrinth, Nico demonstrates his ability to use Ancient Greek to summon the dead.


 * Italian: in The House of Hades, Nico shows that he can speak fluent Italian, as he is Italian by birth.

Demigod Abilities
As a son of Hades, Nico is an extremely powerful demigod. He is considerably more trained in using his powers than most children of the Big Three, such as Thalia and Percy, due to his time spent in the Underworld and he states that he trains with the dead. In The Son of Neptune, Hazel stated Nico was the most powerful demigod she'd ever seen, an impressive admiration given that she knew Jason Grace and dozens of other demigods (though meeting Percy caused her to question this judgment).


 * Geokinesis: He can control the earth - levitating rocks and making them deadly, black, and extremely sharp. Nico can open fissures in the earth that can swallow up creatures and trap them in the Underworld. He can cause earth tremors so powerful, they can shatter the pillars of a mountain fortress. He can also control the black walls of the Underworld. His geokinetic abilities are only surpassed by his half-sister, Hazel Levesque.


 * Necromancy: Nico can summon the dead, put the dead to sleep, and communicate with the dead. He also has divine authority and control over the Furies and the dead. He can banish the dead and release people who should have died (i.e. Daedalus). Some of his abilities in this domain includes the power to destroy Skeleton Warriors and physically manipulating ghosts, such as taking hold of them by hand or forcing them to be silent with a gesture. In The Last Olympian, he was able to summon a fairly large army of undead soldiers by himself. It is unknown how much he has increased in power since then. Hazel once stated that she and Nico each controls an aspect of Hades/Pluto's powers: death (for Nico) and riches (for Hazel). This is a very powerful ability as it literately allows him to have a small army anytime he wants. However, summoning too many undead warriors at one time can cause him fatigue.


 * Telepathy With The Dead: In The House of Hades, Nico warns the Lemures of Venice (angry spirits) to stay away from him, Hazel and Frank by giving off a warning vibe.


 * Sensitivity to Death: He can sense death as it happens or when it is coming; when a person close to him dies, it comes as a ringing in the ears. He can also sense when an immortal is fading, as in the case of Pan.


 * Life Aura: He can sense someone's life aura (he sensed it when Rachel Elizabeth Dare's life aura flickered, and he told her, "I could see you dying.") In addition to that, he has a deep knowledge of the Underworld and knows when a person's life is being judged in the Underworld.
 * Umbrakinesis: He has control over darkness and shadow for various uses such as solidifying it for attacks and to hide in it.
 * Nico can also, dissipate and absorb shadows with his sword, shown during his fight with Clytius, when he kept the Giant's dark aura from affecting his friends.
 * Shadow Travel: He can use shadows as a way of transportation; however, great distances tend to wear him out. The first time he shadow traveled, he passed out for a week. He has said that while learning to use it, he ran into walls and made accidental trips to China. He seems to have gotten better control over it because in The House of Hades, he implied he could use shadow travel to send the Argo II across a mountain range, but was too weak because of his time in Tartarus. When he recovers his strength by the end of the The House of Hades, he decides to transport the Athena Parthenos across the ocean by shadow-travelling about three hundred miles at a time.


 * Induced Fear: He radiates intense fear and death like his father, Hades, but to a much lesser degree. In The Last Olympian, this aura was so strong that Kronos's monsters initially backed away from him. In The House of Hades, he is shown to radiate death from nervousness, as when Cupid intimidates him, "the grass turned brown and wilted" at his feet, as if "poison were seeping from the soles of his shoes."


 * Death Trance: In The Mark of Athena, when he is sealed in the Bronze Jar, Nico shows that he can go into a hibernation called a Death Trance using the seeds of Persephone, which can only be eaten by a child of Hades. The Death Trance induces him to essentially die for a day, meaning he consumes no oxygen and doesn't need any kind of food (besides the seeds).

Percy Jackson
A young Nico had the ability to annoy Percy quite easily, as seen in The Titan's Curse when he asked Percy several questions about his relationship with Annabeth. Nico developed a secret crush on Percy, as he was "Nico’s favorite game, Mythomagic, brought to life." Near the end of the book however, Nico begins to blame Percy for his sister's death, making him much more cynical, but still doesn't let the Skeleton Warriors harm him, and "leaves Camp Half-Blood because of love". Percy, true to character, feels partially at fault and responsible for Nico leaving.

In The Battle of the Labyrinth, Percy receives Iris Messages from Bianca regarding Nico. The two later meet at Geryon's ranch, where Percy makes a bet with Geryon. Nico is included, which angers him, as he shouts that he doesn't want any favors from Percy. After Percy defeats Geryon, he and Nico talk to Bianca, who tells Nico to stop holding a grudge against Percy when it is she he is angry with. By the end of the book, Nico has forgiven Percy. In the last chapter, he appears and informs Percy of a plan he has.

In The Last Olympian, Nico leads Percy to his father's palace in order to gain information on his mother, not knowing that Hades plans to lock Percy up. Percy feels betrayed, even when Nico eventually tries to help him. After Percy bathes in the Styx, he tells Nico to stay and convince Hades to join the Olympians in battle. Nico appears glum, stating that Percy can't trust him anymore. The two join to battle in final battle and Percy forgives Nico.

After Percy has lost his memory in The Son of Neptune, Nico pretends to not know him, and it's later revealed in The Mark of Athena that Hades had told him the time was not right for Percy to know. Once Percy regains his memory, he feels the urge to strangle Nico for not telling him.

In The Mark of Athena, in Percy's narration, it is mentioned that Percy had wanted to strangle Nico about what he did, but doesn't, due to how Nico is after being kidnapped. Nico states (after Annabeth and Percy's fall) that Percy is the most powerful demigod that he knows. During Nico's kidnapping, Percy doesn't give up on finding him, showing that he cares a lot about him. After Nico is rescued Percy can tell that Nico may - or may not - have seen something in Tartarus that shattered him permanently, which shows that they know each other well, despite their previous situations.

In The House of Hades, Nico's true feelings towards Percy are finally revealed when he is forced to admit that his feelings for Percy run deeper than friendship, as he had a crush on Percy. Jason is with him at the time and keeps the secret for him. Percy knows nothing of these feelings and does not return them, though he does care for him like a brother and while in Tartarus realizes Nico is another friend he hasn't treated very well. At some point, Nico had visited Iapetus in the Underworld, and told him that Percy was a friend. It is more than likely that Nico assisted Percy multiple times in the past due to the crush he had on him.

Although Nico states in The House of Hades that he gave up on Percy, there are several parts in the book that imply otherwise. Favionus calls Percy, though not by name, "the one [Nico] cares for most," and Hazel notices that Nico has a pained look in his eyes at seeing Percy and Annabeth hold hands. However, because she doesn't know of Nico's crush on Percy, Hazel believes that the pain is from Nico having gone through Tartarus alone.

When Nico and Hazel Shadow Travel the group out of the Necromanteion, Nico realized that he was holding Percy's hand after everybody else let go, and quickly lets go. Later on, when Nico goes to transport himself, Reyna, and the Athena Parthenos, Percy comes to thank him for keeping his promise and tries to pick up their tattered friendship, Nico, afraid of his feelings, asks Percy to give him space and leave him alone, much to Percy's confusion and hurt.

Annabeth Chase
While their friendship is not mentioned extensively, Nico respects Annabeth and is at times shown to listen to her more than Percy, possibly to annoy him. However in The Battle of the Labyrinth, his view of her improved to the point of friendship, as he chose to save not only Percy, but Annabeth as well when he named himself the Ghost King.

In The Mark of Athena, Annabeth suspects that Nico had a crush on her, although she has no feelings beyond kinship. Furthermore, Annabeth admits that she has always found it hard to "read" Nico and his actions. In The House of Hades, is is revealed that Nico was actually jealous of Annabeth, not in love with her, due to her relationship with Percy, his actual love interest,  which is why Nico initially didn't want to be around her. After seeing Annabeth and Percy holding hands, Nico looks pained, showing that his crush on Percy is as strong as ever.

Leo Valdez
Before meeting him in The Mark of Athena, Leo voices his doubts about Nico's loyalties, infuriating Hazel. Later on, after meeting him, Leo considers Nico creepy, unlike Hazel. They have not gotten to know each other yet, but seem to be on good terms so far, as when Leo is overwhelmed with guilt about not saving Percy and Annabeth, Nico comforts him and assures him that they are alive.

In The House of Hades, Nico seems annoyed with Leo's frustration about constantly rebuilding the masts, saying that they don't grow on trees. Nico corrects him by calmly pointing out that they are made from trees. They seem to both like puns. After Leo returns from Calypso's island, Nico is glad to see him, and shakes his hand.

Frank Zhang
While Nico is kind of mysterious and makes everybody else nervous, Frank doesn't feel the same way and may trust him because of Hazel, as he does not doubt Nico's loyalties in The Mark of Athena, unlike Jason and Leo. Nico, on his part, finds Frank amusing, as stated in The Son of Neptune. In The House of Hades, it is revealed that Frank had always feared Nico, and wasn't sure what scared him more: hordes of restless ghosts or going somewhere alone with Nico. However, after Hazel gets poisoned, Frank is furious with him for not being able to prevent it. Nontheless, when Triptolemus turns Nico into a maize, Frank does his best to save him as well as Hazel, and even slams Triptolemus into a wall for not transforming Nico back. When they reach the Necromanteion, Nico and Frank work well as a team to control an army of undead warriors and defeat Gaea's minions. After they succeed, Nico smiles at him, much to Frank's surprise. They have both played Mythomagic before, though Nico's knowledge of the game is superior, as he had the Africanus Extreme expansion deck. Another thing they have in common is their love for Hazel.

Jason Grace
Jason had meet Nico at Camp Jupiter at once point. Before rescuing him in The Mark of Athena, Jason voices his doubts on Nico's loyalties, infuriating Hazel. In The House of Hades, Jason is the only one who finds out about Nico's crush on Percy and agrees to keep it a secret. His behavior towards Nico also changes after this revelation, and he acknowledges Nico's courage and later defends Nico when Leo calls him creepy. However, when Nico gets infuriated with Jason for telling him to come out, he admits to having seen many angry demigods, but "an angry son of Hades seemed more than he could handle." However, when they reach the Necromanteion, the first person Nico gives the chalice to is Jason, asking him to trust him and take a risk, which implies that he has forgiven Jason and is finally considering to take the risk of coming out. Their rocky relationship corresponds to the one between Zeus and Hades.

Piper McLean
Nico and Piper first meet in The Mark of Athena, after he is rescued. Though no formal interaction is seen between them yet, Nico is definitely thankful to Piper for personally dragging him to safety after he falls out of the Bronze Jar.

Thalia Grace
There is not much known about their relationship. In The Sword of Hades, Thalia only seems to know him as Bianca's little brother and calls him that. Nico doesn't like being called that, but he seems to be on good terms with her. Nico and Thalia have worked well together as a team when they fought the Titan Iapetus with Percy.

Hazel Levesque
"You’re my sister too. You deserve another chance. Come with me."

- Nico to Hazel

In The Son of Neptune, Nico is shown to be very caring to Hazel Levesque, his half-sister, and tries to help her as much as he can. Nico occasionally mistakes her for Bianca, which often reminds Hazel that she isn't the one he was looking for when he entered the Fields of Asphodel. Despite this, the two care deeply for each other, and refer to each other as "brother" and "sister". Nico is one of the few people who know about Hazel's past and was the one who helped her during her blackouts, which shows that he loves his family, even his half-siblings.

The two represent the Greek and Roman form of Hades and Pluto respectively, as in Greece, Hades was known for death and in Rome, Pluto was known for his wealth. Hazel remarks that before she met Percy, Nico was the strongest demigod she had met even though the Romans thought he was harmless. Near the end of the book, Gaea informs Hazel that she has taken Nico and that he should not have gone looking for the Doors of Death.

In The Mark of Athena, when Jason and Leo express doubts about Nico's loyalty, she gets incredibly furious. She was also determined to go to Rome to save Nico despite knowing it could be a trap. After Nico is saved and she sees his broken state, Hazel tries her best to comfort him.

In The House of Hades, when Hazel is dying of poison, Nico goes as far as threaten a minor god to heal her, which results in him being turned into a plant. Later, he kisses Hazel on the cheek as if saying goodbye, to the surprise of Piper. After rescuing Hazel from a giant at the Doors of Death, Nico comes over and kisses her forehead and claims that Hazel 'would have made Dad proud', this sentimental compliment may have reminded Nico of his sister Bianca, who Hades initially considered better than him in every way. Hazel cups her hand around his face and smiles at him, showing they have a very close relationship. She thinks herself very lucky to have a brother like Nico. Still, even she knows nothing about Nico's love for Percy.

Bianca di Angelo
Nico and Bianca shared a very close relationship. As their mother died when they were young, Bianca assumes an almost motherly role, bearing the responsibility that a parent would normally bear, shown when Nico stated Bianca is strict on the movies she lets him watch, before he watched the Orientation Film. This is one of the reasons why Bianca joined the Hunters of Artemis. In The Titan's Curse, Bianca tells Percy that she wanted to know what it would be like to "not be a big sister for one day." Nico felt betrayed when this happened and managed to convince Percy to follow her and keep her safe for him. When Percy failed to do so, Nico was angered and claimed that he could feel her soul being judged, causing Percy to realize he is a son of Hades.

In The Battle of the Labyrinth, Nico is shown to be attempting to bring Bianca back to life through the exchange of a soul for another soul. In search for this soul, Nico meets Percy at Geryon's ranch. Percy tells him that Bianca has been sending him Iris Messages, which angers Nico, as she refuses to see him. Later, Bianca appears. She tells Nico to stop holding a grudge against Percy and it is she that Nico is angry at her, not Percy. Later in the book, Nico is seen talking to Bianca again.

She appears once in The Last Olympian, attempting to dissuade Nico from summoning their mother. Her warning goes unheeded.

In The Son of Neptune, it is mentioned that Nico goes searching for Bianca when Thanatos is kidnapped but finds that she has been given rebirth. Instead, he finds Hazel and brings her back to life.

In The House of Hades, when Jason discusses his revelation to Cupid, Nico angrily tells him that Bianca was the only one who accepted him. Whether this is referring to the fact that he feels like an outcast because he's a son of Hades or whether Bianca knew that Nico was gay is unclear.

Maria di Angelo
Nico has no memories of his mother, which is why he is so eager to discover more information from Hades, who uses this to his advantage at times. He attempts to summon her, despite Bianca warning him that he should not.

In his attempt to summon his mother, he is presented a memory which discusses the terms of the agreement after World War II and how Hades defied it. Nico watches as Hades and Maria discuss how Hades can bring her to safety, though his offer of building her a palace is declined. He then sees Zeus destroy a hotel in an attempt to get rid of him and Bianca.

Hades
Nico and his father share a complicated relationship. They are both extremely similar, especially in their ability to hold grudges. Both of them are also somewhat cynical. However, Nico seems to have a stronger tie to his friends, while Hades seems to have a much darker view of his siblings. Nico is also a more genuine person than his father- Hades can be crafty, as seen from how he used Nico to attempt to trap Percy.

Hades occasionally remarks that it would've been better if Bianca survived, much to Nico's dismay, though deep down, he cares a great deal for his son, as his gaze softened "from steel to stone" when he saw him. He also wants to redeem himself in the Olympians' eyes through Nico, believing his son to be the demigod of the First Great Prophecy. Nico also appears to want to please his father, and beams with happiness when he gains Hades' respect after Kronos' defeat. At the same time, Nico is unafraid to challenge his father in order to do what Nico believes is right.

Persephone
Nico and his stepmother Persephone mutually dislike each other, as he is a reminder of Hades' affair with Maria di Angelo, who Persephone is jealous of. This same dislike appears between Percy and Amphitrite, as well as Thalia and Hera. Persephone appears to take it to another level through turning Nico into a dandelion as stated by him in The Demigod Files when Percy, Thalia, and he ended up in the underworld together.

In The Mark of Athena, it is revealed that Nico carries around some pomegranate seeds from Persephone's garden in case of an emergency, and so uses them when he is trapped by the twin giants. It is unknown how Persephone feels about Nico using an item from her personal garden, or if she is aware at all.

Camp Jupiter
To everyone at Camp Jupiter, Nico is just a traveling outcast, and they consider him as harmless as a Faun, though Hazel knows better. However, Reyna and Octavian grow suspicious when Nico seems to know about Alcyoneus in the meeting. Camp Jupiter proclaims him as the Ambassador for Pluto.

Iapetus/Bob
After the Titan lost his memory, Nico would visit him at his father's palace. He would convince Bob that Percy was a good person, which would eventually lead to the Titan helping Percy and Annabeth reach the Doors of Death from inside Tartarus.

Magical Items

 * A Stygian iron sword. It is three feet long, and in The Last Olympian is described as being "black as a nightmare." It helps Nico to channel his power to control and summon the dead, and it can also drain souls to give the sword more power. Only Hades, his children and Clytius can use Stygian Iron for their weapons.
 * He is seen wearing black armor in The Last Olympian with a skull shaped visor.
 * A skull ring shown in The Battle of the Labyrinth, The Last Olympian, and The Son of Neptune. Twisting it makes the nearest dead restless. He usually uses it to relieve tension.
 * Mythomagic figurines and cards. He throws them into a fire in anger during The Battle of the Labyrinth.
 * In The Battle of the Labyrinth, he had a pair of Daedalus' wings, but after he used them, he threw it away in a trash can.
 * A red travel rose that he didn't use, given to him by Persephone, in The Sword of Hades.
 * Pomegranate Seeds-magical seeds from the Underworld. If he places them on his tongue, he can go into a death like trance that allows him to use less air and energy, in the event he is captured. This allows him to go into what is called a "Death Trance," which he uses to sustain himself during The Mark of Athena.

Etymology

 * The name Nico is the diminutive form of Nicolò or Nicola, the Italian form of the Greek Nikolaos (Nicholas), meaning "victory of the people." It is most likely intended to evoke the prefix necro-, meaning dead. His surname is Italian for "of the angels" alluding to his role as the Lord of the Dead's son.
 * Nico is also a form of Nike, goddess of victory.
 * His surname, "di Angelo," means "the angel," in Italian.
 * The full meaning of his name is 'the Angel of the Dead'.

Trivia

 * The line "With great power...comes great need to take a nap." is an obvious reference to one of Spider-Man's most famous lines: "With great power, comes great responsibility", albeit a bit altered for comedic effect and to indicate that Nico's powers tire him greatly, prompting him to take naps every now and again to regain his strength, as he did at that moment in The Last Olympian.
 * Nico's physical description (pale skin, dark hair, brown eyes, black clothes, and an aura of death) also fits Rick Riordan's description of Anubis, the Egyptian god of funerals, in The Kane Chronicles trilogy.
 * The first time he met Mr D., he called him "The wine dude", which irritated the god, but he forgot about it soon after.
 * Nico has been to a New Orleans graveyard, though it is unknown why he went. Interestingly, this is one of the favorite hangouts of another death god (Anubis, the Egyptian god of funerals). It was also the place that his half-sister Hazel Levesque lived just before her death.
 * Nico and Jason Grace have similarities:
 * They both have older sisters, whom have both been/are Hunters of Artemis.
 * They have both been to Camp Half-Blood and Camp Jupiter.
 * They have godly stepmothers (Persephone, Juno).
 * Both have lost their memory. Nico's because of being dipped in the River Lethe and Jason's was removed by Juno (though Jason's is temporary; in The House of Hades he seems to be recovering from his amnesia, much like Iapetus).
 * Hazel Levesque and Nico's mothers share similar first names: Marie Levesque and Maria di Angelo.
 * Nico's birthday is undecided. Rick Riordan has stated on two different occasions his birth-date: January 28th, 1924 and May 16th, 1924. However, the year would be way off since in The Son of Neptune, Hazel stated he was only a few years younger than her. Another contradiction comes from The House of Hades where in Nico mentioned that he was about six years old when he first visited Diocletian's private residence in "[nineteen] thirty-eight or so". This would put his date of birth at around the early 1930s.
 * In the series, he is described as having long, shaggy black hair, but in his portrait he has short brown hair. Also, he seems to have green eyes instead of brown, and not as pale of skin.
 * He is the only child of the Big Three to never have gone on an official quest. However, he, Percy, and Thalia were given the task of retrieving the then unfinished sword of Hades, and succeeded. As well as aiding the seven in closing the Doors of Death.
 * Unlike his half sister Hazel, horses don't like Nico (as Porkpie, one of Blackjack's friend once stated: "He smells like the dead.")
 * Most animals don't like Nico due to him smelling like death, and the feeling is often mutual.
 * Nico speaks fluent Italian.
 * Nico has the ability to control ghosts. However Melinoe is the goddess of ghosts, not Hades.
 * As of The Mark of Athena, Nico is the first known demigod ever to have returned from Tartarus alive but even as a son of Hades, his stay in Tartarus left him shattered and more withdrawn.
 * Percy speculates, when on the verge of death and seeing Tartarus as it really is, that Nico had seen it that way the whole time, and that even a few moments of seeing it was maddening. He wonders how Nico had survived with his sanity.
 * Nico has been transformed into plants twice in the series: into a dandelion by Persephone during a "family spat" shortly before the The Demigod Files, and into a corn plant by Triptolemus in The House of Hades.
 * As of The House of Hades, Nico, is the only known homosexual demigod, something he has been trying to hide for years. The only blatant clue is in The Titan's Curse, when he asks Percy if Annabeth is his girlfriend.
 * In both the Percy Jackson and the Olympians and the The Heroes of Olympus series, Nico ensures the fulfillment of the Great Prophecies: Nico helps Percy gain the Curse of Achilles, which enables both Percy and Luke to defeat Kronos ("the hero's soul cursed blade shall reap"), and Nico tells Iapetus that Percy is a friend, which induces him to follow Percy and Annabeth to the Doors of Death ("foes bear arms to the Doors of Death").