Charles Xavier: After losing the use of his legs, Charles Xavier began taking a serum that enabled him to walk, but at the cost of his telepathic ability. When he needs his powers in 1973, he must quit the serum and use a wheelchair.

Bone Claw Wolverine: Projecting his mind back to 1973, Wolverine must take control of his younger body and re-unite the X-Men to stop Mystique from causing a horrific future where humans and mutants are both endangered.