Quote Originally Posted by VargasVermillion View Post
Both sephiroth and kefka are insane to the point of being a threat to everyone but themselves alone but The circumstances surrounding them are quite tragic, fairly avoidable cases that simply lead to an extreme. For anyone that doesn't know Kefka is mad due to being one of the first to get magitek enhancements when the tech was still in development. Although I don't think this was mentioned in FFVI itself.
It actually was. If you talk to all the people in the cafe/pub of vector when you enter the first time you will see one of them mentions this.