I firmly don’t believe that Bart went to blackwing for ken, ken was an “added bonus” I guess you could say. Bart felt like she screwed EVERYTHING up, she told Francis that and that’s why she wouldn’t stay with Panto/Francis in Wendimoor.

I think Bart went to blackwing because she felt like she deserved punishment. She felt like blackwing was the sole place she could be where she wouldn’t hurt anybody. When she was with Panto she didn’t have to because he slayed, but when she was alone her only option was to do as the universe guided and become the holistic assassin we saw so much of during season one. But as soon as the people she loved (ken) started getting hurt she stopped her path of destruction and led as peaceful of a life as she could. But as soon as Panto got hurt, despite her giving up killing people, she killed everyone, she killed an entire army by herself.

So Bart didn’t go to blackwing to be with ken, she went to punish herself and to protect others from her. She knew blackwing was the “most boring place ever” and the only place she could be where the universe had nobody for her to kill except ken.