Typically, moons are associated with the mythological god for which their planets are named. For instance, the Martian moons Phobos and Deimos are named for the sons of Ares, the God of War. Mars is Ares' Roman counterpart. Pluto's other three moons, Charon, Nix and Hydra, are affiliated with Hades and the underworld just like Pluto. You can vote on existing possibilities or write in your own suggestion.