Zagreus, Prince of the Underworld, is the son of Hades and is the protagonist of the game named after his father. Zagreus has always had a sense that he doesn't belong in the House of Hades. Sometime before the start of the game he decides, against his father's will, to escape from the Underworld—no matter how many tries it might take him. He is aided and encouraged in his journey, primarily by his caretaker Nyx and his mentor Achilles. Others outside the House of Hades, such as Sisyphus, Charon, and the Olympians sometimes offer their aid as well.

(Source; https://hades.fandom.com/wiki/Zagreus)