2 Works in X-Men Reverse Bang
When Charles sees the dragon on his balcony, he suspects that he's losing his mind. When he starts hearing voices, he's certain of it, and the realization that magic is real is little comfort when these newfound abilities threaten to destroy his life. He has no choice but to accept his enigmatic neighbor's offer of training in exchange for a promise - that he will repay that favor, when asked to.
Like many promises in the world of magic, however, this turns out to have unexpected consequences.
Erik stayed, but he has doubts. Charles can walk, but it isn't always painless. Learning to adapt in more ways than one can be fun, but it isn't without its dangers.