Callisto is a character appearing in American comic books published by Marvel Comics and is associated with the X-Men. She is the leader of New York City's subterranean mutant settlement the Morlocks, until losing that post in a duel against Storm. Storm subsequently leaves the group in Callisto's care as her representative, and the two eventually form an uneasy alliance.

Storm is a superhero appearing in American comic books published by Marvel Comics. Created by writer Len Wein and artist Dave Cockrum, the character first appeared in Giant-Size X-Men #1. Descended from a long line of African witch-priestesses, Storm is a member of a fictional subspecies of humans born with superhuman abilities known as mutants. She is able to control the weather and atmosphere and is considered to be one of the most powerful mutants on the planet, and one of the most powerful beings in the Marvel Universe.