He was the third god I'd met, but the first who really struck me as godlike" (19.86). Hades is a member of the Big Three and he governs the land of the dead – the Underworld. He reminds Percy of Napoleon or Adolph Hitler in appearance. Percy describes him for us: "He was at least ten feet tall, for one thing, and dressed in black silk robes and a crown of braided gold. His skin was albino white, his hair shoulder-length and jet-black. He wasn't bulked up like Ares, but he radiated power. He lounged on his throne of fused human bones, looking lithe, graceful, and dangerous as a panther. (19.87)
He's not happy to see Percy when Percy ventures to the Underworld, especially when Percy accuses him of stealing Zeus's master bolt and demands that Hades give it back. Hades believes that Poseidon has sent Percy on a quest to steal the master bolt and his helm of darkness. The helm of darkness is his symbol of power which allows him to, to "melt into shadow or pass through walls. He can't be touched, seen, or heard. And he can radiate fear so intense it can drive you insane or stop your heart" (13.76).
Hades is having issues in the Underworld. He asks Percy,
"Have you any idea how much my kingdom has swollen in this past century alone, how many subdivisions I've had to open?" (19.110)
The increase in the amount of dead people entering his kingdom has resulted in traffic problems, the need for more security ghouls, double overtime pay for his staff, and more. He tells Percy that he used to be an incredibly rich god, because he governs everything underground – including precious jewels like diamonds, rubies, and emeralds.
Hades is famous for abducting his wife, Persephone, and forcing her to marry him. Persephone is Demeter's (the goddess of the harvest) daughter. Persephone negotiated a special arrangement with Hades, allowing her to stay with her mom in the living world for six months of the year. Apparently, when Persephone is around, Hades is much nicer. Unfortunately for Percy, it's summertime, which means that Persephone is living it up above ground.