Why do the exiles companions follow her even if shes evil?

I've been doing an evil run of KOTOR 2, and while doing my evil acts my companions keep remarking that they "don't know why theyre doing this" or "dont know whats coming over them". It especially doesnt make sense why Bao-Dur and Brianna stand for me just murdering innocents especially as they say theyre against that. Is it explained why they choose to follow her lead and help her with these kind of cruel acts, even if they disagree?