Ganymede

Ganymede was a Trojan prince, and a very attractive mortal, which led Zeus to abduct him, in the form of an eagle, to serve as cup-bearer to the gods, replacing Hebe.

History
Ganymede was abducted by the Lord of the Sky from Mount Ida while Ganymede was tending a flock of sheep. Zeus saw him and fell in love with him, either sending an eagle or turning himself to an eagle to transport Ganymede to Mount Olympus.

In addition Zeus is said to have taken Ganymede as his eromenos.

The Sea of Monsters
Ganymede's voice can be heard advising users of the Gray Sisters taxi service to use the 'seatbelt' (a black chain).