The Ending Of X-Men: First Class Explained

Lehnsherr agrees with Shaw's goals but stops his plan as a matter of personal revenge, since it was Shaw, posing as a Nazi commander, who killed Lehnsherr's mother at Auschwitz to draw out his mutant powers. He kills a helpless Shaw, over Xavier's protests. There's at least a decent argument to be made that Shaw was too dangerous to remain alive, and Xavier is, in a way, complicit with the act of killing him. It's his telepathy that freezes Shaw in place and shuts down his mutant ability to absorb kinetic energy.

Instead, what Lehnsherr does next represents the schism. The combined forces of the American and Soviet fleets turn their weapons onto the beach where the mutants have fought, seeking to exterminate this new threat. But Lehnsherr stops their shells and missiles in midair, turning them around and sending them back toward the ships. Xavier pleads with him to stop, and physically attacks him, trying to pull off the helmet Lehnsherr took from Shaw that blocks the intrusion of telepaths.

Now the stakes are very high. The conflict seems destined to have one of two endings from which there will be no repairing of their relationship. Xavier would never forget the thousands of innocent deaths if Lehnsherr bombards the ships. Lehnsherr could never forgive Xavier taking direct control of his mind to stop him. But the film chooses a third way: CIA agent Moira MacTaggert (Rose Byrne) emerges from a crashed plane to fire her pistol at Lehnsherr. He easily deflects the bullets with his powers, but one of them strikes Xavier in the lower back, paralyzing him.

It's his remorse that finally breaks Lehnsherr's concentration, leaving the missiles to crash into the sea. Xavier's inadvertent sacrifice saves the day, and allows their relationship to stay in that familiar frenemy zone.