Hades is the god of the Underworld and one of the Big Three (along with Zeus and Poseidon). He is described as a greedy, heartless, and deceitful figure dressed in swirling black robes inlaid with the faces of tortured souls. He rules the Underworld on a throne of human bone. Percy notes that Hades “radiated power” and that he is the most “godlike” out of any of the deities that he has met thus far. Percy, Annabeth, and Grover travel to Hades’s domain because they believe he stole the master bolt to start a war with his brothers. After all, a war would add a plethora of souls to his kingdom. However, when the trio actually meets Hades, they realize that he is not the thief. Hades is a red herring, a literary term for a clue intended to be misleading or distracting. Within the context of The Lightning Thief, Hades is meant to distract the heroes, and subsequently the reader, from suspecting the real culprits: Kronos, Luke, and Ares.
Hades is a complicated character. On the one hand, he is cruel to Percy and his friends and holds Sally hostage until Percy does his bidding. He also sends the Furies after Percy. However, Percy does extend some sympathy for Hades when he realizes he constructed his kingdom to be an exact replica of Olympus. Percy acknowledges that getting banished from Olympus would make anybody “bitter.” His empathetic treatment of Hades highlights his noble character and illustrates Percy’s heroism—not just because he is a gifted fighter, but because he is a genuinely good person.