As many of you know, Master Xehanort was the most manipulative and dangerous villain yet seen in the KH series. But if you read his reports, you 'll notice that he once had good intentions.
So that raises a question: how did he fall to darkness? Here are a few thoughts of my own of how he fell to darkness (purely speculation):
1. He fell in love with a girl (a fellow Keyblade apprentice, if you will), and he helplessly watched her get killed by their master. Her death threw him into a state of anger, and he begins to rely on the power of darkness. He then murders his master, and feels satisfied about it. Also, because he was betrayed by his master, he no longer wants to show mercy, because his love wasn't shown any.
2. Xehanort begins to question the power of light and why darkness is so dangerous. He slowly tests some of his dark power, and admires it.
Just some ideas. What about you guys? What would be some interesting ideas of why Xehanort is the way he is now?