|“||Seek the caverns, near the springs of blue. Oh, Apollo.....your sanity will be taken away, but do not.....||”|
Hyacinthus was the son of Pierus of Magnesia and Clio, the Muse of History. Due to his extreme handsomeness, two gods fell in love with him: Apollo and Zephyros. However, Hyacinthus chose Apollo over Zephyros.
While playing a game of quoits with Apollo, Hyacinthus was killed by a jealous Zephyros. In his grief, Apollo refused to let Hades take Hyacinthus away, and instead transformed Hyacinthus' corpse into a flower - the hyacinth.
While trying to retrieve Diocletian's scepter, Jason Grace and Nico di Angelo meet with Zephyros, still in the service of Eros. Zephyros, in his Roman aspect Favonius, provides an explanation as to why he serves the god of love. He recounts the story of Hyacinthus. He tells about the jealousy he had felt for Apollo and Hyacinthus's closeness. Jason is initially surprised by Favonius falling in love with a man, but he recovers quickly.
Apollo also confesses that Hyacinthus and Daphne are his greatest and favorite lovers. Apollo tells that he is reminded of the few months he spent with Hyacinthus when he sees his son Will Solace with his boyfriend Nico di Angelo.
After his meeting with Rhea, Apollo falls into a dream where Hyacinthus appears as a ghost, talks to him for a very brief time and asks him to find the caverns near the blue springs. When Hyacinthus starts fading away from the dream, Apollo desperately reaches and grabs his lover's shoulder and begs him not to leave him. But he wakes up, holding a pot of hyacinth flowers, and later comes to know he was talking to the flowers.
When Apollo sings to tackle the Myrmekes, he sings of his love for Hyacinthus and expresses his regret over his jealousy which ultimately killed Hyacinthus. He also tells that he created the hyacinth flowers out of his dead lover's blood, to always keep him in the sunlight.
Apollo continuously grieves for the loss of Hyacinthus, as he is constantly reminded of him everywhere he goes while in human form.
When Apollo meets Meg McCaffrey again, he says that he had never been so happy to see anyone, including Hyacinthus in his amazing tuxedo on their date night.
When Apollo, Meg and Grover Underwood solve puzzles to get to Herophile, one clue is Named for Apollo’s fallen love, this flower should be planted in autumn. Set the bulb in the soil with the pointy end up. Cover with soil and water thoroughly... you are transplanting. Apollo got reminded of Hyacinthus so runs down the eight squared corridor. But they actually had to fill in the "..." to make the word unless. And, as a result, the trio nearly get burned by the essence of Helios. Meg got mad at Apollo, complaining that he made the hyacinth flower, but Apollo retorts that not all gods, like Prometheus, know everything about their creations.
In The Hidden Oracle, Hyacinthus was described by Apollo to be "the most handsome of men", with skin that is either bronze or copper-hued, curly dark hair, eyes as purple as senatorial robes, and a kind brilliant smile. However, in Apollo's dream, he had an ugly dent above his left ear where the discus had struck him.
Though it was never specifically stated or confirmed, it was highly likely that, as the son of Clio, the Muse of History, Hyacinthus possessed powers associated with history, memories, and time, though to a lesser extent compared to his mother. Possible examples of such powers were:
- Past Manipulation: Hyacinthus presumably had the ability to manipulate or alter the past.
- Retro-cognition: Hyacinthus presumably had the ability to discern events that happened in the past.
- Memory Manipulation: As history and memory are intertwined, Hyacinthus presumably had the ability to control and manipulate memories.
- Prophecy: As history and time are also intertwined, Hyacinthus presumably had the ability to see into the future.
At some point, Apollo fell in love with the handsome mortal man Hyacinthus. One day, Zephyros, the god of the west wind, who was also smitten by Hyacinthus, came across him and Apollo playing a game of quoits. Jealous that Hyacinthus preferred the radiant archery god to him, Zephyros shifted the wind and sent a heavy metal ring flung by Apollo right at Hyacinthus’s head, instantly killing the youth. The devastated Apollo would turn his lover's deceased body into a flower, the hyacinth. In order to avoid Apollo's wrath, Zephyros would seek protection from Cupid who had mercy on him because he was driven crazy by love, who forced the guilt-ridden wind god to work for him forever as a result. As mentioned in The Hidden Oracle, Hyacinthus would forever remain one of Apollo's two all-time favorite lovers (on par with Daphne).
At some point, Zephyros fell in love with a mortal man named Hyacinthus, whom he found "quite extraordinary." After finding Hyacinthus with Apollo, playing a game of quoits, Zephyros accidentally killed Hyacinthus in a jealous rage. As the mortal died, Apollo transformed him into a flower, a hyacinth. Aphrodite's immortal son, Eros, offered Zephyros protection, on the condition that he would work with him forever.
Because Pierus of Magnesia was the king of Magnesia, Hyacinthus was a noble himself. Pierus loved Hyacinthus and took care of him very well. When Hyacinthus was a teenager, Pierus taught Hyacinthus both martial arts and archery.
Because Clio is the Muse of history, Hyacinthus was very fond of history. Clio loved Hyacinthus dearly. When Hyacinthus was a teenager, Clio was the parent who taught Hyacinthus history to make sure he didn't make the same mistakes as his ancestors.
Since his mother, Clio is the Muse of History, it is likely that Hyacinthus knew them. Additionally , Hyacinthus probably does respect the Muses to some extent, since they are his aunts.
- It is quite possible that Hyacinthus could turn back to a human since Thalia was able to come "back to life".
- Since he's a demigod son of Clio, one of the Muses and a daughter of Zeus, Apollo is Hyacinthus' uncle.
- The hyacinth flowers Apollo held were either red as the blood of Hyacinthus or had the violet hue of his eyes.
- Just like Daphne (another lover of Apollo), Hyacinthus was transformed into a plant (although he had been transformed by Apollo instead of Gaea).
- When Hyacinthus tells Apollo to find the caverns near the blue springs, he was referring to the Cave of Trophonius located in the Bluespring Caverns.
- It is unknown where he "rests", though he possibly still resides in Greece, close to Sparta