From EA only perspective, I am confused by others responses here. We have 5 companion options and I don't think I'd describe any of them as evil.
Devs mention somewhere that they wanted to showcase the "evil" characters first, because people were complaining on the evil protagonist gameplay previously, to polish it up better, and will add the good ones later on. So that's got me thinking, if those characters really that "evil", or they just have a possibility to develop as evil, depending on your actions
