Leo Valdez

"I'm coming back for you, Calypso. I swear it on the River Styx."

- Leo to the night wind

Leonidas "Leo" Valdez is one of the seven heroes of the Prophecy of Seven. He plays one of the most important roles in the prophecy. He is a Greek demigod, the son of Hephaestus (Roman form Vulcan) and Esperanza Valdez. He is currently in a relationship with Calypso.

History
Leo was born on July 7th, in Houston, Texas to the mechanic Esperanza Valdez and the god Hephaestus. When he was little, he had a babysitter named Tia Callida, whom later was discovered to be Hera in disguise. She was watching Leo because she knew of his destiny as one of the seven in the prophecy. She tried to "kill" him multiple times by putting him in an active fireplace and by letting him play with knives. She also tried to make him poke a rattlesnake, which he refused to do. This was done to help train Leo to be strong at a young age. He once drew a picture of a flying boat with a bronze dragon head as the masthead in crayon at the age of five and just as Leo was going to sign his name on the picture, it was blown away by the wind. Tia convinced him to use his abilities to start a fire to "warm these old bones," and he ended up burning his handprints into the table. In The Blood of Olympus, Leo recalls how he used to play with plastic organ models as a kid. He once got in trouble after turning a cross-section kidney and some skeleton legs into a kidney monster and scared the school nurse.

At the age of eight, Leo was visited by Gaea, the Earth goddess, whom intended to break his spirit, after being notified by Medea that he would have a crucial part to play in her downfall. Horrified, Leo tried to use his pyrokinetic abilities as defense to save his mother and himself, but Gaea manipulated the fire, burning the mechanic shop. His mom died in the fire, and his Aunt Rosa called him a 'diablo' （which means devil in Spanish） and turned his remaining family against him, thus forcing him to be sent to several foster homes.



The death of his mother haunted Leo for years. The emotional strain caused him to run away from multiple foster homes. After running away for the sixth time, Leo was sent to the Wilderness School, where he met Piper McLean, who unbeknownst to him, was a daughter of Aphrodite. When Hera switched Percy Jackson and Jason Grace, she manipulated the Mist so Leo would think Jason was his best friend, although they became real friends later on. He is said to be the only living son of Hephaestus that is able to generate fire.

The Son of Neptune
While Percy is dreaming, he sees Leo working on the Argo II when one of the engines explodes. He claims that it could take two or three days to fix and that the deadline to have the ship completed was today. When Percy, Frank, and Hazel are watching Polybotes from afar Ma Gasket, the Cyclops from The Lost Hero yells, "The camp, yes. Vengeance! The orange and purple ones destroy my home. Now Ma Gasket will destroy theirs! Do you hear me, Leo? Jason? Piper? I come to annihilate you!"

Later, when visiting Hazel Levesque's house in Alaska, Percy sees a picture of Sammy Valdez and thinks he had seen him somewhere before, but can't remember where. Hazel says he would be much older and Percy must just be imagining things. Percy then remembers his dream figuring out that Leo resembles Sammy almost identically.

Upon returning to Camp Jupiter and the defeat of Polybotes, Leo appears on a video scroll that was sent to Percy through Ella. He told them that he would appreciate it if the Roman demigods didn't shoot them out of the sky when they come to rescue Percy and start their quest. While watching the video, Hazel mistook him for Sammy Valdez and Percy remembers the picture of Sammy when looking at Leo.

Leo Valdez and the Quest for Buford


When Leo accidentally polishes Buford with Windex instead of Lemon Pledge with extra moisturizing formula, Buford runs off with two syncopators essential to building the engine for the Argo II. Leo, in a panic, asks for Jason and Piper's help to retrieve them. He explains the situation of how in about an hour, dangerous chemicals will mix in the engine blowing up the forest portion of Camp Half-Blood without the syncopators. With everyone caught up, the three friends journey into the forest in search of Buford. They then encounter Maenads on their journey and Leo feigns to be the Greek god, Dionysus, to please the Maenads. Suspicious, the Maenads figure out the truth and chase Leo and his friends until Leo comes up with an idea. Leo sends Jason to go find Buford, while he and Piper run towards Bunker 9. Once they reach Bunker 9, Leo distracts the Maenads with a  party while he sets up a trap to ensnare them. Leo finally sets off the trap which drops a net (based on the original net which Hephaestus used to catch Ares and Aphrodite together) on the Maenads. Jason just in time arrives with Buford and Leo fixes the syncopator in the engine of the Argo II, thus narrowly preventing a massive explosion at Camp Half-Blood. Later Chiron and Argus arrive and decide to deport the Maenads away.

Between the Series
Several days after the deaths of Gaea and Leo, a parchment scroll with a holographic message, sent from the resurrected Leo, came fluttering into Camp Half-Blood on the wind. Leo recorded the message while flying on Festus' back, and in it, he reveals that he has managed to get resurrected and find Calypso, and apologizes for leaving his friends and fellow campers in such a manner. However, the message is not of perfect quality, so the latter portions of it are filled with static. He ends the message by stating that he loves them all, and cheerfully asking for tacos to be cooked for his arrival. The scroll is later kept by Nico di Angelo, who takes to looking at it every time he begins to get angry at Leo.

Leo later mentions that during his long journey back to Camp Half-Blood with Festus and Calypso, he had flown through the Sea of Monsters (encountering Polyphemus along the way), and had an embarrassing experience in Albania (with Nico hastily shutting Leo up before the latter can get into the details).

The Hidden Oracle
Six months after Gaea's death, Leo, Calypso, and Festus finally return to Camp Half-Blood after the camp is almost destroyed by the Colossus Neronis. The campers take numbers from Nico di Angelo, so they could both welcome Leo back and punch him, as well as a few campers he never met and Chiron (with Nico himself being the last one to do so). After some discussion, Leo and Calypso decide to go on the quest with the former god Apollo.

The Burning Maze
He and Festus arrive at an airfield in Santa Monica but is distraught over Jason’s death, wishing he could have seen the son of Jupiter one last time. He then dicusses on what happened during Caligula’s attack on Camp Jupiter. He says the Twelfth Legion Fulminata managed to ward off the attack, however their were many casualties (minus Frank, Reyna and Hazel) and the camp is in ruins. The son of Hephaestus insists on taking Piper McLean to Oklahoma on his way back to Indiana.

Percy Jackson's Greek Heroes
While narrating the adventures of Theseus in this book, time after Leo's return in The Hidden Oracle. Hence, Leo is therefore most likely attending the monthly Argo II reunion party that Percy is worried about being late to.

Personality
"I try not to think. It interferes with being nuts."

- Leo Valdez Leo is easygoing, mischievous, upbeat, energetic, eccentric, funny, flirty and loves to tell jokes constantly, even if they aren't particularly funny. He is usually a troublemaker, as he gets in trouble constantly with Coach Hedge for tampering with his megaphone. Leo is genuinely very intelligent and honest, and cares about his friends and family. He sometimes doesn't think before reacting and he enjoys pulling pranks on people, especially those who he doesn't like. Despite his jokey attitude, Leo is emotionally scarred from the death of his mother and is crushed by guilt as he indirectly caused her death. He later realizes that it wasn't him who had caused her death, and opens up to his friends more and more. He hides a hurt and angry demeanour with humour. Leo has been shown to have a serious side, which happens when he is angered by someone or when the situation calls for it. He is also seen building small bits of machinery and equipment and is very skilled and serious about his work.

He is also known to frequently fall in love with any beautiful girl as long as she is completely out of his league, such as in the case of Khione and Thalia. For example, when Thalia, Jason and Leo were in the cave alone, Leo asked Thalia if her no-dating policy was seasonal, but she ignored him. Khione herself being a snow goddess, hates Leo as she can sense the fire within him and takes his compliments (Leo once called her hot) as insults. It is possible that this characteristic comes from his father, Hephaestus.

Near the end of The Lost Hero, he starts to let go of the pain of his mother's death and learns that his pyrokinesis is a gift and tool, not a curse. He also decides to stop running from his past and he starts opening up to his friends more. As of The House of Hades, after Leo visiting Calypso for the first time, Leo became more steady and yet heartbroken, but he still made jokes, albeit less frequently. Facing heartbreak from this experience almost seemed to age him somewhat, often seeming sad and far off, thinking of Calypso and his promise to her. Leo's maturation after meeting Calypso is quite typical of someone who experiences heartbreak after a lifetime of feeling like an outcast. It is also revealed here that Leo's favourite colour is red.

Even with his mischievous personality, Leo is also a leader, as he is the counsler of the Hephaestus cabin, and is a commander at the Argo ||.

He is also seen as being incredibly brave and selfless in the sense that he was willing to sacrifice himself to stop Gaia and his heroism was inspiring to Frank and Hazel who tearfully embraced him before the final battle.

Fatal Flaw
While Leo's fatal flaw has not been revealed, he shows feelings of inferiority - being unwanted or not trusted, the one no one wanted. He also can say the wrong things at the wrong time, as shown in the Dark Prophecy when he is held captured by one of Commodus' men, a Germani named Albatrix.

Appearance
In The Lost Hero, Leo is described by Jason to look like a "a Latino Santa's elf," with curly black hair, dark brown eyes, pointy ears, a cheerful, elf-like face, normally with a mischievous and impish smile on his face, and a diminutive stature with a slim and relatively scrawny build. He is 5'6, about the same height as Piper McLean. Leo's most notable trait is that he has a look in his eyes that makes him look like he has taken much more caffeine than the normal limit; this could be linked to his ADHD, although he is described as being seriously ADHD even by demigod standards, according to Annabeth. Although, not being quite as handsome as Jason, Percy, and Frank, Leo has been called 'cute in a scrawny way' by nymphs and the Maenads from Demigod Diaries, indicating that Leo is quite good-looking for a son of the ugly god, Hephaestus. He also, 'invented scrawny'.

During House of Hades, Hazel noted Leo's curly hair had gotten longer and shaggier, his face got leaner, so he looked less like an imp and more like 'one of those willowy elves in the fairy tales". His eyes also constantly drifted, as if he was trying spot something over the horizon.

Abilities and Tools
General Abilities= As a member of the seven and a son of Hephaestus, Leo is extremely powerful and had displayed excellent battle skills even without formal training.
 * ADHD: Like most demigods, Leo possesses inborn supernatural battle reflexes and senses that he uses to analyze the fighting style of his opponent. According to Annabeth, however, Leo is seriously ADHD, even for a demigod.
 * Dyslexia: Leo's brain is hard-wired for reading Ancient Greek instead of modern languages.
 * Morse Code: Leo's mother taught him Morse code, a skill he has retained, and he was therefore able to understand Festus' last wish. As of The Blood of Olympus, Leo and Annabeth are the only known demigods to know Morse code.
 * Trilingual: Leo can speak Spanish, Greek, and English fluently, having learned both English and Spanish from his mother as a child, and knowing Greek naturally because of being a demigod.
 * Genius Intellect: Leo is very intelligent. He had learned to think three-dimensionally, and solve mechanical problems in his head. Even at the age of eight, he can do math better than most adults. He is very clever and witty, and is good at adapting, letting him build at any circumstance. He had used his wits, which helped him survived in tough schools and neighborhoods, and a master problem-solver.
 * Superhuman Strength : Being a demigod, Leo is stronger than a regular mortal. Although, Leo as been many times labeling himself as 'weak' because of his small stature, and is definitely the weakest male demigod of the Seven; indicating Leo is pretty weak for a demigod. Leo also is extremely skinny and short and doesn't look very strong. However, Leo has been shown to be quite a lot stronger than he looks, as he used two silver-tipped blacksmith hammers to smash full-grown monsters that got in his way.
 * Superhuman Agility : Being a demigod, Leo is more agile than a regular mortal as he was able to twist his body in mid-air to hang on to a ledge of a cliff after flung off. He was even able to easily launch himself in a backwards somersault to avoid getting crushed by rocks thrown by the Earthborn.
 * Superhuman Durability : Being a demigod, Leo is more durable than a regular mortal as he shook off falling from dozens of feet, shake off crashing to Calypso's island from a high distance, able to survive crashing face first in the ocean from dozens of feet, and many feats. In The Lost Hero, when Piper, Jason, and him fell from the sky, crashed into a ceiling, and slamming on a metal catwalk, he and Jason was able to walk away from it with no signs of discomfort.
 * Cooking Skills: Shown in Lost Hero, Leo is an amazing cook.
 * Superhuman Reflexes : Being a demigod, Leo's reflexes are faster than a regular human. Leo was able to dodge thrown projectiles by the Cyclopes, dodge rocks thrown from the Earthborn, and was quickly able to jump off from a helicopter before it got crushed. He was even close of catching a mechanical snake in Blood of Olympus. The explanation of why Leo is so fast could be because he's very ADHD even for a demigod.
 * -|Demigod Abilities=


 * Fighting skills: Despite receiving no known formal combat training, during the battle at the Wolf House in The Lost Hero, Leo displayed considerable combat skills by using two silver-tipped blacksmith's hammers to "smash any monsters that got in his way," even while fighting Khione, the ice goddess in the same time.
 * Technokinesis: Leo has amazing mechanical abilities (even for a child of Hephaestus); he can manipulate a megaphone to say "The cow says moo" in a low voice like Darth Vader's and build a working helicopter out of pipe cleaners. He was able to fix the mechanical dragon Festus in one night, even though the rest of the Hephaestus cabin thought it was beyond repair and had to be destroyed. He even added wings to the dragon so it could fly.
 * Machine Aptitude: Leo can understand and sense machinery and has the ability to expertly operate machines he has had no prior experience with. He can also communicate with machines such as Festus.
 * Machine Expertise: Because Leo is a demigod child of Hephaestus, he can instinctively fly or drive any mechanical vehicle expertly, including trains, or helicopters. (He can drive cars too, though it makes him carsick, as shown in The Mark of Athena).
 * Machine Sensitivity: He can sense faults in metal ore and identify machinery type and use by touch.
 * Trap Detection: Leo can also sense traps, in particular mechanical traps, shown when he saw the hidden trap meant to catch Festus in The Lost Hero, and when he knew where all the defense mechanisms were in Midas's yard and disarmed them remotely.
 * Pyrokinesis: He is the first demigod child of Hephaestus in hundreds of years to master the ability of pyrokinesis, the ability to generate and control fire. At low-level ability would probably be moving a candle back and forth; if better, maybe putting out the flame with his mind or making it relight. Pyrokinesis is one of the more practiced skills like telekinesis. It is too, for warming people up or setting objects aflame. His pyrokinesis is supposedly a curse, but he is determined to interpret it as a gift. His pyrokinetic abilities can go as far as to shoot white hot flames high in the air that could burn through a metal chain link, and by causing powerful explosions from impact from his fireballs. He was able to easily keep the upper hand against the snow goddess Khione for an extended period of time forcing her to go on the defensive, eventually forcing her to flee. An impressive feat given that fighting a god/goddess is "suicide," this is made even more impressive by the way Leo was going to completely overpower Khione and this could show Leo's power is comparable to that of a child of the Big Three. Jason had even noted that Leo was the only reason why they were still alive, since the heat from his fire was able to melt almost all the ice from the Wolf House. However, sometimes he has trouble controlling his pyrokinesis when he gets excited or scared, beginning to heat up and smoke. He can throw fireballs/fire bolts, fire blasts and (if he concentrates hard enough), columns of fire. However, this ability had no effect on the Gigantes Clytius.
 * Superheated Fire: Leo can increase the heat of his fire (to the point that it becomes white-hot), and can also create walls of flame. This is the main defensive use of his powers.
 * Supernova: Leo can increase the heat of his fire to such an extent that he basically becomes like a supernova. He was able to use this ability to defeat Gaea in The Blood of Olympus, but the side-effects effects of using his power in such a way were fatal to him (enough to char his otherwise fireproof body), despite his immunity to flames. Though it is possible this is survivable now, because as his fire usage and immunity are strained, they get stronger.
 * Fire Immunity: Leo discovers he is fireproof (he can even survive a kerosene barrel explosion without feeling any pain in The Lost Hero, unlike Jason who feels the pain of heat but is unharmed by lightning). For example, when he was a small baby, Hera (in the form of Tia Callida, his "insane" babysitter) puts him in a blazing fireplace and he is completely comfortable. However, when he was attacked by Festus' firebreath, it did sting him slightly. Many other things like this follow. However, Leo's supernova fire explosion (combined with Octavian's onager projectile) in The Blood of Olympus was fatal even to Leo, enough to char his body.
 * Heat Sensitivity: He can sense heat and flames, even allow him to walk through the forest at Camp half Blood at night in The Lost Hero, in the form of thermal vision.


 * -|Magical Items=
 * Magical Toolbelt - He has a magical tool belt that he uses constantly. He can pull simple tools from the belt, as well as food, medical supplies, and breath mints. The belt is seemingly endless and he doesn't know where it all comes from. However, larger items, especially things that don't have to do with mechanics, require the belt to recharge or "cool down." It is also known that big items, such as chain-saws, or magic items, like Jason's sword, Ivlivs, cannot be pulled out of the belt.
 * Hammer - His primary weapon is his 3-pound Club Hammer, which he summons from his tool belt from time to time.
 * Festus the Bronze Dragon - was repaired and managed by Leo after his discovery of Bunker 9, used in the American Civil war as the Hephaestus bunker. He supported Leo, Jason, and Piper, all the way to Midas's mansion, where he was destroyed by lasers to save Leo, Piper, and Jason. He was later used as the figurehead of the Argo II. By the end of the Blood of Olympus, Leo has secretly repaired Festus, building him a new body in the Argo II. After Leo sacrifices himself to stop Gaea, Festus brings him back using the Physician's Cure.
 * Holographic Scroll - Leo's own invention, used in The Son of Neptune to alert Camp Jupiter, that the Argo II is coming.
 * Buford - Leo's magical three legged table.
 * Archimedes Sphere - Leo found it in Archimedes' workshop and repaired it. After that he was upgrading the sphere an made several copies. He can use it in different ways.
 * The Physician's Cure - Ancient healing potion that can bring back the dead. The Seven put it together as part of their plan to defeat Gaea and Leo gave it to Festus who used it to resurrect him after Gaea's defeat.

Love Interests
Calypso= ""I'm coming back for you, Calypso," he said to the night wind. "I swear it on the River Styx.""

- Leo as he leaves Ogygia

In The House of Hades, Leo lands on Calypso's island, as the gods had not seen to Percy's wish of setting her free from Ogygia, her cursed home. Although Leo and Calypso do not get along very well when they first meet, when he works to escape, she turns out to be a great help and they become friends. They also share a kiss just before Leo leaves. Leaving Ogygia, Leo doubts that he really is "in love with an immortal girl" and that Calypso is in love with him. He then swears upon the River Styx that he will come back for Calypso. When he returns to the world, it is clear that he misses Calypso: Jason notices that he has lost most of his nervous energy and has the same heartbroken expression that he saw from Nico.

In the The Blood of Olympus, Leo is obsessed with returning to Calypso after he has defeated Gaea. Once Gaea is gone, he returns to Ogygia and takes Calypso back into the mortal world. "Nah, we were absolutely destined to meet your hot sister."
 * -|Thalia Grace=

- Leo talking to Jason about Thalia

When Leo meets Thalia, Jason's sister, he falls in love with her right away. Leo hits on her, but Thalia showed no signs of even acknowledging him. Leo took this as her not wanting to show how impressed with him she was, even though she was simply ignoring him. When he and Jason explained what had happened on their quest so far, Leo played up his own abilities. He also asked Thalia if the "not dating" rule all the Hunters of Artemis had to swear to was permanent or just a seasonal thing. Thalia, however, just looked at him as if he had evolved from pond scum, which only made Leo like her more. "Lady, nobody messes with my dragon and gets away with it. I can’t believe I thought you were hot."
 * -|Khione=

- Leo to Khione

When first meeting Khione, Leo states he acted like a total fool, but couldn't help it. While Jason and Piper where upstairs talking to Boreas, Leo had his clothes cleaned, his hair brushed, and took a pack of breath mints from his toolbelt in hopes of impressing her, but ultimately failed. When meeting Khione again at the Wolf House, Khoine tried to use Leo's attraction to her against him. Saying that he could join her and become her champion, instead of following the path the Fates had given him. Leo on the other hand rejects her because of what she had done to Festus and comments that he can't believe he thought she was hot, something Khione, the snow goddess, takes great offense to. "Leo was determined never to forget Echo’s face. She deserved at least one person who saw her and knew how good she was. Leo closed his eyes, but the memory of her smile was already fading."
 * -|Echo=

- Leo leaving Echo

Echo is a nymph that Leo met while on an island in the Great Salt Lake. While Leo originally teases her, as she is forced to repeat the last thing she hears, he stops after Hazel Levesque tells him to stop (as well as Echo turning his words against him). After meeting Narcissus and seeing how absorbed he is in himself, as well as all the nymphs loving him for his looks, he realizes that Echo is the only one that truly loves him for him and wants to save him. Echo helps Leo in his plan to steal a metal shield Narcissus is using as a mirror and aids in Leo's escape. While running away, she plans to fight off the nymphs that are after them. Leo sees her true face for only a minute and offers to bring her with them, but she refuses as she still loves Narcissus.

Friends
Piper McLean= Piper and Leo have been friends for a long time, meeting at the Wilderness School shortly before The Lost Hero. Piper trusts him enough to tell him the truth about her father Tristan McLean, who is a famous movie star. Leo knows enough about her to know that she doesn't like when people fight her battles for her. When he was given fake memories by the Mist about Jason Grace, he had feelings of become a third wheel to Jason and Piper, something that begins to happen again when Jason and Piper start getting close all over again. Despite Piper being very beautiful, Leo never hits on her or asks her out, acting more like a brother who looks out for her. In The Mark of Athena, Piper gives him a sisterly kiss on the cheek after he returns safe and sound from Camp Fish-Blood, showing that she really does care for him, even if the two sometimes tease each other. She also isn't upset at Leo for shooting down on Camp Jupiter, and sticks up for him, since she claims that Leo for her is "like the annoying little brother [she] never had", promising to always stick up for him. In The House of Hades, when Leo returns from Calypso's island, Piper is one of the first ones to hug and kiss him, showing a very strong friendship between them. Leo was also the one of the first to praise Piper's unexpectedly beautiful singing in The Blood of Olympus

After Leo's death in The Blood of Olympus, Piper is devastated, and several days later, she and Jason do their best to remember all of the cheerful memories associated with Leo and stay up all night on the roof of Cabin 1 in the process. Part of her is still hopeful that Leo has somehow survived, despite all odds.

In The Hidden Oracle it is revealed that after Piper and Jason listen to the holographic scroll and learn of Leo's survival (several days after Gaea's), they are exuberant, and tirelessly search for him for most of September, until Chiron finally persuades them to resume their school year.

In The Burning Maze Piper and Jason break up, shortly after which Jason dies. Piper tells the story to Leo when he arrives with Festus. She is sobbing and hugging him while she shares the story. Leo comforts her and orders her to ride back to Oklahoma with Festus as it is on his way back to Indianapolis.

Piper and Leo's back-story is a rare one, since they are the only two known demigods who meet and befriended each other before they even knew they were demigods.

Despite their time at the Wilderness School being a trick from the mist in The Lost Hero, Leo still considers himself Jason's friend. He even volunteers to go on a quest with him, and goes to repair the Bronze Dragon to give them a means of transportation. Despite Leo and Jason being good friends, Leo cannot help but feel jealous of Jason. People look at Jason and respect him for being the son of Zeus (really Jupiter), while he only sees himself as the lowly mechanic. He also feels left out as Jason and Piper start to reform their relationship. The only time Leo doesn't feel jealous of Jason is when Thalia talks to Jason about his past and how Hera had taken him away from their mother. Leo remembers that while his own life wasn't that good, his own mother wasn't possessive of Hephaestus and only wanted Leo to know him.
 * -|Jason Grace=

Jason, on the other hand, harbors a great deal of respect for Leo, and is inwardly ecstatic when Leo offers to accompany him on the quest to save Hera. He acknowledges his ability to keep him and Piper alive in The Lost Hero, noting that their quest would have failed if not for him. Jason feels more at ease when around Leo, as he requests that he stay with him during his talk with Thalia for support. Even after Leo fires on Camp Jupiter due to the influence of the Eidolons, Jason (along with Piper) does not blame Leo, confident that he would never actually do such a thing despite the other demigods' doubts.

Jason remains one of Leo's closest friends throughout the series, and is devastated after Leo's death in The Blood of Olympus. Several days later, he and Piper do their best to remember all of the cheerful memories associated with Leo and stay up all night on the roof of Cabin 1 in the process. Part of him is still hopeful that Leo has somehow survived, despite all odds.

In The Hidden Oracle it is revealed that after Jason and Piper listen to the holographic scroll and learn of Leo's survival (several days after Gaea's), they are exuberant, and tirelessly search for him for most of September, until Chiron finally persuades them to resume their school year. Later in The Burning Maze, it is revealed that Jason dies in the hands of the third emperor, Caligula before which Piper and he would have broken up. Leo is informed of his death by Piper McLean. He hugs her as she narrates the story is thunderstruck by the fact that Jason is no longer there. He asks Apollo and Meg McCaffrey to take him to Camp Jupiter for the right Roman burial. Percy and Leo first meet in The Mark of Athena, but Percy saw images and visions of Leo during The Son of Neptune. They're not particularly close and haven't gotten to know each other well yet, as Percy was initially angry at him for shooting on Camp Jupiter. When Percy was mad at him, Leo was scared, as he recognized the look that reminded him of the times Jason summoned lightning. The two have also shown the same sense of sarcasm and, at times, a degree of ignorance. At the end of The Mark of Athena Leo is filled with guilt because he thinks opening Nemesis's fortune cookie was the reason Percy and Annabeth fell into Tartarus, in spite of Hazel and Nico's objections. Leo then vows to do whatever it takes to rescue Percy and Annabeth from Tartarus, despite thinking someone would have to stay in there to close the Doors of Death from both sides.
 * -|Percy Jackson=

In The House of Hades, after meeting Calypso, Leo becomes quite angry and resentful at Percy for seemingly abandoning her, as well as somewhat jealous, since Calypso clearly still had feelings for Percy (which made things "ten times worse" for Leo). Ultimately, however, Leo is the one to save Percy and Annabeth by flinging a screwdriver at the Doors of Death, managing to open them just in time.

By The Blood of Olympus they've finally gotten to know each other somewhat. Leo admits to feeling awkward hanging out with Percy, since he wasn't sure what kind of small talk to make with a recent survivor of Tartarus. He admits that Percy and his impressive powers had been intimidating enough before, with Leo having trouble of even thinking of Percy as part of the same camp as him, since the two of them had never been at Camp Half-Blood at the same time. The only things the two of them had in common are their silly senses of humor and Calypso, and every time Leo thought of the latter, he wanted to punch Percy in the face. He had wanted to discuss the subject with Percy for days, yet the timing had never seemed right, and the subject had gotten harder and harder for Leo to broach as the days went by. They finally manage to talk about it while attempting to fight Nike and her minions. Percy admits to feeling bad about Calypso, feeling that he's failed her, recalling how he'd experienced Calypso's grief after seeing her curse on Annabeth take effect. Percy admits to his mistake without making excuses, admitting that he should have made sure that the Olympians had kept their promise to free her. He is happy about Leo finally finding her, and promises that if he and Leo survive the ordeal at hand, that he'll do anything he can to help Leo find a way back to her, insisting that this is a promise that he will keep. As a result, Leo is finally able to let go of his anger for the son of Poseidon, admitting that he "just couldn't dislike the guy" any longer, due to the latter's sincerity, and is calmed by the confirmation that Percy didn't return Calypso's past feelings.

The two are shown to be very friendly around each other after that, with Leo even nicknaming Percy "Aquaman", much to the latter's chagrin, and also teasing Percy about his Zodiac sign being a Leo. Like the others, Percy is devastated at Leo's death in The Blood of Olympus, and remains hopeful in the possibility of Leo still somehow surviving.

When Leo finally returns in The Hidden Oracle, Percy is so overjoyed to see him, that he, unlike most others, embraces Leo without even punching him.

Some of the things Leo and Percy have in common is a goofy sense of humor, them both having traveled through the Sea of Monsters and encountered Polyphemus, and them both having been marooned on Ogygia, becoming a love interest of Calypso in the process.

Leo cares for Annabeth, but has been somewhat afraid of her ever since they first met at the Grand Canyon in The Lost Hero. The two have gradually bonded in The Mark of Athena through engineering and machinery, since aside from Leo, Annabeth is the only one who can operate the engine room of the Argo II. Annabeth is often shown to be in awe of Leo's skills with building, and is also the person that made Leo change his mind about the 'stupid blondes' stereotype. When he arrived at the Pantheon, Leo thought about how Annabeth would react to seeing it ("If Annabeth were here, she would've spent the whole day talking about it."). He is filled with guilt when she and Percy fall into Tartarus, feeling he is responsible. Ultimately, however, Leo is the one to save Annabeth and Percy in The House of Hades by flinging a screwdriver at the Doors of Death, managing to open them just in time. Like the rest, Annabeth is devastated at Leo's death in The Blood of Olympus
 * -|Annabeth Chase=

Interestingly, both of them can communicate in Morse Code. 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 and intimidating, unlike Hazel. They have not gotten to know each other yet, but seem to be on relatively good terms so far, as when Leo is overwhelmed with guilt about not saving Percy and Annabeth, Nico comforts him and assures Leo that they are still alive.
 * -|Nico di Angelo=

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. Much like Frank and Jason, Leo is very much intimidated by the son of Hades, and never dares to tease him to his face. Nico, being far more serious, is frequently annoyed by Leo's sense of humor. However, after Leo returns from Calypso's island, Nico is glad to see him, and shakes his hand.

In The Blood of Olympus, when Hades reveals to Nico that one of the Seven is destined to die, the idea of any of them (including Leo) dying made Nico feel empty — like he was back in the Giants' Bronze Jar, alone in the dark, subsisting only on sour pomegranate seeds. Though they weren't close, Nico is devastated by Leo's death (having actually felt it happen), and is very guilt-ridden, since Nico feels like him choosing not to prevent Octavian's death unnecessarily cost Leo his life. While not ready to forgive himself, Nico assures Hazel that she is blameless and does his best to comfort her, later praying to his father for guidance.

In The Hidden Oracle it is revealed that a resurrected Leo was able to send a parchment scroll with a holographic message several days after his and Gaea's deaths. While almost all of the campers are both exuberant and furious, Nico is affected more deeply than most (due to him having blamed himself for Leo's death), and therefore he keeps the scroll in his pocket long after other campers had finished re-listening to it, and he resorts to looking at it whenever he wants to get angry at Leo. When Leo finally returns, Nico is in charge of having the other demigods get in line to both punch and greet the returned son of Hephaestus, with Nico being the last one to do so.

Interestingly, some things that Nico and Leo have in common, is that they both used to hold a grudge against Percy (albeit for very different reasons), they both tend to fall in love with very attractive people that are completely out of their league (Thalia and Percy respectively), they both fluently speak a Romance language (Italian and Spanish respectively), they have both witnessed their mothers' deaths at the hand of a deity (Zeus and Gaea respectively), they both considered it "so cool" to be a demigod right after finding out, they have both faced Lycaon (with Nico killing him), they have both had an embarrassing experience in Albania, and they have both run away from places they used to call home (Camp Half-Blood and multiple foster homes respectively). Hazel and Leo first meet in The Mark of Athena, but are very awkward around each other from the get-go. Leo always feels like Hazel is watching him for some reason, but doesn't know why. He is also confused when she asks him if his name is Sammy, which it isn't. He also tries to avoid her to a small degree as he knows that Frank is dating her, but the two seem to end up together (sometimes with or without Frank). However, the two keep finding themselves in awkward situations that leads to a fight between Hazel and Frank.
 * -|Hazel Levesque=

While riding across the Great Salt Lake on Arion to get the Celestial Bronze needed to fix the Argo II, Leo holds Hazel's waist, noting that his heart is racing in doing this. He dismisses it, claiming it to be because of the speed they were going. Later, he calls her pretty.

Their connection to each other is slightly cleared up when Hazel uses her ability to show people the past to show Leo who Sammy was. During this flashback, it is shown that Sammy is Leo's great-grandfather and that he asked Leo to look after Hazel for him. Despite learning this information, the two are still somewhat shy of each other.

In The House of Hades, most of the rough patches in their relationship are smoothed out, and they act more openly friendly towards each other. When Leo returns from Calypso's island, Hazel kisses him on the cheek, showing that she loves him as a brother. She is also instantly able to see that Leo has fallen in love, something nobody other than Jason could guess. Later, when she and Leo get stuck in the Necromanteion, Hazel apologizes for telling Leo about Sammy, but Leo fully embraces his identity as Sammy's "stunt double" and encourages Hazel not to question her relationship with Frank.

In The Blood of Olympus, it is revealed that Hazel had finally gotten Leo to spill about Calypso. She then sketched him a picture of her based on the description that he'd given her. Shortly thereafter, Leo tells his suicidal plan only to Hazel and Frank, since they, as Romans, would understand the importance of sacrifice. Touched by Leo's heroism, Hazel and Frank tearfully embrace Leo in a group hug and support his plan, even though they despise it. Hence, when their plan of successfully resurrecting Leo after Gaea's defeat seemingly fails, Hazel is understandably devastated, and hesitant to ask Nico if he'd felt Leo's death. Frank initially disliked Leo in The Mark of Athena, partly because he was afraid of how the latter could manipulate fire, and because of his relationship with his girlfriendHazel. Frank is also uneasy about Leo at first because of his similarity to Hazel's former love interest, Sammy Valdez. The two have contrasting personalities: Frank being far more serious and Leo's lack of control of what he says and his tendency to tease Frank. Frank often walks in on Hazel and Leo talking, which annoys him. When they were at the great Salt Lake, Frank scowled when he found out Leo was going with Hazel to get Celestial Bronze and lime, initially not understanding Leo. When they were attacked by the Skolopendra, Leo forgets the Sonar and Coach Hedge complained: 'Maybe if you hadn't been staring into Hazel's eyes, holding hands for so long-'. Frank was enraged and demanded an explanation, though when Leo offers one, Frank calms himself. He also argues with Leo a lot, like when Hazel was pinpointing her brother, Nico's location in Rome. Frank agreed to accompany her but when she invited Leo to come too, "His smile turned into something more like Chrysaor's mask" as Percy puts it. However, near the end of The Mark of Athena they seem to have made up, and act like friends, with both of them discovering that they lost their mothers to fire, and Leo complimenting Frank's ability to speak Chinese.
 * -|Frank Zhang=

In The House of Hades, it is revealed that the main reason Frank was initially so hostile towards Leo was due to his father's voices constantly ordering him to kill him. Frank is very thankful when Leo gives him a special fire-proof bag for his burned stick.

By The Blood of Olympus, the two have become good friends, and Leo tells his suicidal plan only to him and Hazel, since they, as Romans, would understand the importance of sacrifice. Touched by Leo's heroism, Frank and Hazel tearfully embrace Leo in a group hug and support his plan, event though they despise it. Hence, when their plan of successfully resurrecting Leo after Gaea's defeat seemingly fails, Frank is understandably devastated. Though, they have never actually had a full one-on-one conversation, Reyna dislikes Leo with a fierce passion, due to the fact that he attacked Camp Jupiter with the Argo II in The Mark of Athena, even though it was not his fault, as he had been possessed by an Eidolon. However, Reyna isn't known for being a forgiving person, and so probably still dislikes him. However, on Ogygia, Leo is shown to be concerned for her safety, as he grew all frantic upon seeing the attack by the gryphons on Reyna and Scipio just as the video goes dark. Reyna, on her part, despite her former dislike of him (which she seems to have finally gotten over by that point), was very saddened by Leo's death in The Blood of Olympus.
 * -|Reyna Ramírez-Arellano=

Interestingly, several things both Leo and Reyna have in common is that they both speak fluent Spanish, albeit slightly different dialects (Mexican and Caribbean respectively), they have both faced Lycaon, and they have both had an embarrassing experience in Albania. Will was the one to first explain to Leo in The Lost Hero what it means to be a demigod, tell him about Percy Jackson and the Titan War, while taking him on a tour of Camp Half-Blood and the Hephaestus' Cabin. Leo considers Will "pretty cool" and the tour itself "amazing". Will is also among the first to punch and greet Leo in The Hidden Oracle.
 * -|Will Solace=

Family
Esperanza Valdez= Leo is shown to love his mother very much. Esperanza is very protective and caring of him. The two had a very strong relationship and Leo was devastated when his mother died. He blames himself for her death, and for that reason, didn't use fire again until he needed to in order to help his cabin.

"She said Hazel’s great danger would not happen in my lifetime. But I promised I would be there for her. You will have to tell her I’m sorry, Leo. Help her if you can."
 * -|Sammy Valdez=

- Sammy talking to a baby Leo

Leo has met his great-grandfather, but was not old enough to remember. The name 'Sammy' sounded familiar to him, but he couldn't place who it was. After looking at Hazel's past, the memories showed a moment where an old Sammy was talking to a baby Leo. Leo and Sammy have very similar personalities and appearances, which is shown when Hazel believes Leo to be Sammy. Leo however feels that he is only an imitation of Sammy after seeing Sammy's quick wit and how charming he was with the girls, unlike himself.

When Leo and Hephaestus first meet in The Lost Hero, it began with Leo telling him off for disappearing from his life. Hephaestus laughs at this, saying Leo reminds him of Esperanza, whom he misses quite a bit. Hephaestus later reveals that he has been watching Leo, and that he is very proud of him. He also admits that he is not very good with people, which is why he doesn't meet with his children often. When Festus is destroyed, Hephaestus takes his head to Bunker 9 upon Leo's request. In The Blood of Olympus, they meet again, and courageously fight the Giants side by side.
 * -|Hephaestus=

Leo hates his Aunt Rosa. After Leo's mom died, she blamed Leo for the death, calling him a devil. She turned the entire family against him, leaving him with no where to go. Because of her refusal to take him in, Leo was sent to a foster home, and his life of running away began. When Leo meets Nemesis he sees her in the form of Aunt Rosa, meaning she is the person he wants revenge from most.
 * -|Aunt Rosa=

Though not much is shown of Nyssa, Leo's first impression of her is that she is very serious. This is because of the Curse of Cabin 9. She is the one who explains the curse to him, and she congratulates him when he returns from his quest. She also helped him work on the Argo II, along with the rest of the Hephaestus cabin.
 * -|Nyssa=

Trivia

 * He is currently the only known living son of Hephaestus who has been given the gift of Pyrokinesis. The previous one is Thomas Faynor known for having caused the Great Fire of London in 1666.
 * Because of his pointy ears and his friend Jason Grace calling his dad Vulcan instead of Hephaestus, Leo claims that he doesn't even like Star Trek, a reference to Spock, one of the main characters of Star Trek who is a Vulcan.
 * He is the only one of the seven to not have lived in California at any point in life.
 * The name Leo is one of the three zodiac signs which has fire as it's element.
 * In Latin, Leo means "Lion".
 * In Teutonic, Leo means "Bold to his people".
 * Leo, Nico di Angelo, Frank Zhang, Nyssa Barrera, Reyna Avila Ramírez-Arellano, Hylla Ramírez-Arellano, Annabeth Chase, and Hazel Levesque, are the only known demigods that can speak two or more languages (that has nothing to do with them being a half-blood), as he, Nyssa, Reyna and Hylla can speak Spanish, he and Annabeth speak Morse Code, Nico can speak Italian, Hazel can speak Louisiana French, and Frank can speak Canadian French, along with "a little" Chinese.
 * Leo looks almost exactly like Sammy Valdez, Hazel's old boyfriend from the 1940s.
 * This is because Sammy is his great-grandfather, as stated in The Mark of Athena. Leo jokes that Sammy could be his stunt double.
 * While Leo is a son of Hephaestus, he shares many traits with the children of Hermes, including elvish ears, a mischievous smile, and a love for practical jokes.
 * It is said by Annabeth that even by demigod standards, Leo is seriously ADHD.
 * Leo is the only known demigod who can go toe-to-toe with Khione and not freeze to death.
 * Leo Valdez and the Quest for Buford is in his point of view.
 * Leo's is the only known case of a demigod who met and befriended another demigod before either knew they were demigods.
 * Leo once reprogrammed all the electronic billboards in Times Square to read "ALL DA LADIES LUV LEO!" ("accidentally", of course)
 * It is stated in The Mark of Athena that Leo gets carsick.
 * Leo has a cousin named Raphael and an aunt named Rosa, both of whom Leo doesn't like very much.
 * In The Mark of Athena, Leo says "One basketball to rule them all".  This is a pun on Lord Of The Rings, "One ring to rule them all".
 * The Lord Of The Rings is Rick Riordan's favourite book series when he was younger.
 * Leo's least favorite line in the prophecy is "To storm or fire the world must fall".
 * He and Hazel Levesque are the two people out of the Seven that have died and been resurrected.
 * Although Jason Grace might also qualify as resurrected, as Jason's soul was charmspoken to return to his body by Piper McLean in The Lost Hero, though that was due to Death being chained up at the time, as revealed in The Son of Neptune.
 * His favorite color is red.
 * Leo is the second known child of Hephaestus to die in an explosion. The first one was Charles Beckendorf.
 * Leo is the only male demigod of the Prophecy of Seven who wasn't praetor of the Twelfth Legion.
 * Leo is the only demigod that had run away six times from foster homes.
 * Leo is the only person to find Ogygia twice.
 * Leo is the only character who appears in both the very first and the very last scenes of The Heroes of Olympus series.
 * In The Blood of Olympus, it is inferred that Leo had an abusive foster mother, Teresa.
 * It is surmised that Leo's full name is Leonidas, as Calypso once called him by it.
 * In The Lost Hero, Leo's motto is revealed to be "keep moving."
 * Leo is also a constellation in the sky.
 * In The Dark Prophecy, it is stated he does not like being called short.
 * Out of the seven, Leo had the most lines in the prophecy that were about him, or partially about him.
 * Leo and Annabeth are the only two of the seven who have run away from home.
 * Though Jason was taken from his mother and sister when he was younger.
 * Leo is the first known demigod of Mexican decent, the second being Alex Fierro.
 * Leo's birthday is July 7th, further indicating his place as a seventh wheel.
 * The recurring idea of being the seventh wheel associated with Leo may have something to do with his eventual sacrifice, as seven means 'ghost' in Chinese (as stated by Frank's grandmother).

Léo Valdez