I honestly get Rachel's point. She was told she wasn't special. And it showed that she didn't have courage. She should have stopped there, but she didn't listen, and instead she has caused a chain of events to unfold.
Headon wasn't really a villain for telling Rachel to kill Bam, but it just goes into the notion of, "The BE the Man, you've got to BEAT the Man."
Rachel though was still a coward, she pushed Bam instead of digging a knife. Everything would have stopped there, but instead she caused another ripple by thinking she got rid of Bam. I don't see her as a villain, but a catalyst of shyt that will fukk up the Tower because Rachel is the TRUE Irregular; a person that isn't suppose to be there, causing calamity.
Bam isn't a Irregular IMO, because he has the skills to do it on his own.