he could of whent into slytherin

He could have gone into Slytherin who, as we find out in DH, are apparently all evil, sans two; he could have joined Voldemort; he could have succumbed to the feelings he was having in book five and just attacked everyone.

He had the all brains, the ambition and the motive for revenge which could have made a psycho out of him.

Slytherin is not in itself evil. But Bella was never a nice person to begin with. She manipulated the people around her and cared nothing for the people who cared about her. She was pretty much evil and manipulative from the get go but Meyer's strange view of the world has glorified this abhorrent behavior.

I honestly don't think he would have become evil if he went into Slytherin I Firmly believe that

and i never even though about bella turning evil. it never looked like it would happen

^ For Harry I was more so drawing on his parallels with Voldemort in that he could have turned out like him and that he had part of his soul in him, though I agree that theres something in Harry's personality not really compatable with evil.

For Bella I was thinking about when she turned into a vampire, theres always the risk that she'll give into her bloodlust and not want to be a 'vegetarian' but I get where your coming from

theres lots of times in the books when Harry's on the verge of evil, especially in Order of the Phoenix