James McAvoy
and Michael Fassbender play Professor Xavier and Magneto, respectively, in this June's 'X-Men: First Class,' (in theaters June 3) which will show the early stages of what would become a decades-long, and really quite complicated, relationship.

While it's too soon to know exactly how they meet in the movies, it seems clear that they find each other at the best possible moment: before mutants become a growing concern and an object of fear for humans. The central conflict that develops between the two men after that moment is their disagreement over exactly how to handle this new human-mutant relationship. Xavier, ever the peacemaker, thinks it vital to show humans that mutants are not a threat. Magneto thinks otherwise. He believes that he was born better than humans and has little reason to kowtow to what he sees as their tyranny.

We'll have to wait until 'X-Men: First Class' hits theaters to get the full details, but that's OK -- Xavier and Magneto have an well-fleshed-out history in comics already, and Moviefone will get you up to speed.