Xavier is a character introduced in Beautiful Redemption. He was formerly a Keeper and after standing up to Angelus of the Far Keep he is transformed into a hideous creature. He was eternally trapped to being the Gatekeeper of The Far Keep in the Otherworld.
Xavier was a Keeper to one of the many Caster libraries.
Xavier heard noises and screams in the dungeons of the far custodian and went to tell Angelus, Xavier realized Angelus was doing experiments and was changing the Caster Chronicles. He confronted him and told him that he should not do that because he was a mortal. Angelus stole the blood from a Light Telepath who he loved, but she eventually went crazy from the experiments and blood transfusions and was destroyed.
Xavier wanted to report Angelus, but with his powers, turned him into a hideous creature that had sent him to take care of the distant gates custodian. for he was the guardian of the gates of the gates.
Xavier was transformed into a creature different from anything else in the series. He is described with a bald head; smooth, grayish skin; big, dull green eyes that aren't quite Caster green; and wings that resemble a bat's. He says that if he moved too far from the Far Keep, he would continue changing further from the man he once was, and that he was once as Mortal as any other Keeper.
Xavier is a hoarder and everything he salvages is important to him. Powerful caster objects in his possession include The Book of Stars and The Book of Moons. He also has a Third Eye, a cobalt-blue sphere the size of a baseball, that allows you to see a specific memory in the past, and amulets. Among this, he has miscellaneous other things, like rocks, birds, candy necklaces, and a Snoopy lunch box.