Jeremy Kathof could not take what has been done to him. His family abused him, his friends abandoned him, his sole mate never returned his affections.
He cannot stand to put himself into more pain, so why not put other ponies in pain instead?
Sure it SOUNDS like a bad idea, but he is a psychopath, he can't distinguish right from wrong!
(The "Bad Ending" of the B,B,P,C,S... series, and no, not a sequel, prequel or anything of the sort. Not even a 'separate' chapter of the story for those moderators out there...)
(Side note: This is written in a fashion that shows the thought process of a deranged pony. He does have a sense of "goodness" in him, but this is a story that shows what happens when a good pony lets his bad emotions take the better of him. So if you don't like dark reads, then this is not the story for you.)