I always figured that it was more than just being the high school geek that had scarred him. Things went wrong somewhere, and he found comfort in following a rigid set of rules, and trying to force others to, as well. That never goes well.

The flip side: maybe he was the imaginative math teacher, good at getting his students to think, friendly with them, until something happened; maybe he had a party at his house, someone got into trouble for drinking... ;-)

Also, I can't BELIEVE I typo-ed "quiet." Grrrrr.