He's a visionary, with all the moral ambiguity and arrogance that includes. He wants to do the right thing, but has a power that can easily be used to manipulate others. The X Men universe makes great use of that moral struggle in the friendship between Charles and Max (aka Magneto). Magneto sees the inherent bad in people and wants to protect against it; Charles sees the inherent good and wants to trust to it. They're both wrong and right, and are proven so by circumstances, which makes for some good dramatic tensions.
Like Nick Fury, Charles Xavier isn't always perfectly forthcoming about his plans, and what he wears close to his chest might be dangerous to others, despite the best of intentions. He's a great character for ensemble stories like the X Men, because he can be the lynchpin that holds the group together, or the point where loyalties divide.
Don't forget to check out my own superhero stories. Change of Life, book two of my Menopausal Superheroes series just came out a few days ago!