Well, in Rant's case it's more that he later became a misfit. Towards the start of his tour of duty he was normal, but it's just Morel's Reach that messed with his head.
Like I said, you really don't want to know what that Dominatrix did to him (although I'll give you a clue; when it came to killing the beast, he had to literally climb onto the back of its neck and blow its head off with half a dozen demo charges)