Two young men, Charles Xavier and Erik Lensherr, discover their mutant powers and initially work together to stop a global threat, only to become archenemies after a rift forms between them, leading to the eternal war between the Brotherhood and X-MEN.

X-Men: First Class
The origins of the X-Men saga unfold in the 1960s, where Charles Xavier and Erik Lensherr, two influential mutants, initially collaborate to locate others with similar extraordinary abilities.