It was not for a quest, but Percy and Annabeth decided to talk to Hades personally.

"What brought the Heroes of Olympus here, to my humble home?"

"We uh-" Percy said

"Bob and Damasen," Annabeth said,"We want to talk to them. Thank them."

"You missed something, daughter of Athena," Hades smirked,"Bob is here, but Damasen is in Tartarus, you want to talk? Be my guest."

"Fine. Let's go Percy, just a quick trip won't hurt."