X-Men: Everything You Need To Know Before Marvel's Big Relaunch

Again, this is slightly old news, though the how and the changes that Xavier has experienced are things that most probably do not know of.

In Charles Soule's Astonishing X-Men, the team journey to the Astral Plane in order to rescue Charles from the clutches of the Shadow King - a feat which they manage to achieve. This is done by Fantomex giving up his body so that the Professor could inhabit it, meaning that, for one, Xavier now has the uncanny ability to grow hair along with his telepathic powers.

Upon his return Xavier asked to be called 'X' and also seemed to be a tad more manipulative (and perhaps even evil) than before. He convinced Fantomex to give up his body which raised eyebrows, and he wiped everyone else's memory after he was saved. Though that's not to say that Xavier was the nicest of characters beforehand, it's still suspicious.

Basically, if 'X' turns out to be the villain of Hickman's run, then don't be surprised.