Xavier father is a world famous psychic who is the only parent not to visit on parents' day, so he's got those issues. Along with the race he's having visions, his paintings, showing him murder and violence. Might make anyone a little moody. Add in being a teenager, and there you go. As for getting his way, it's established early in that he is used to getting his way as the weird "big man on campus" archetype, with a goth bent of course.