[spoiler topic]
Last night, I was thinking of the flashback during Jessica's flashback during her contract mission. Not exactly strange, but I thought it was weird that Jessica bit Ashe after she killed her POS boyfriend/vampire master. But after having done a full playthrough of the (current) game, I think I made a discovery.
After defeating Charlotte and rescuing the queen, Ashe gave Anja her blood after bargaining for the dark orb. I always thought she was just re-energizing/healing the princess after knocking her out. But then I remember Bianca and how she tried to drink Ashe's blood during her backstory. I always thought it was weird that remembering her grandmother was the trick to snap her out of a vampire mindset. But combined with the other clues, I realize that it's something else.
For the longest, I thought to make a vampire docile, you just have to kill the vampire that turned them. But now I think that's the extra step you need to make to stop them from going back to being evil. The real trick is Ashe's blood and somehow drinking causes the vampire to (mentally) return back to how they were as a human.
I strongly believe this theory now and I think you (MKRU) were foreshadowing this from the start. We probably will receive an explanation in chapter 5, I would like to know if the power can be given to anybody else or something unique to Ashe. I also wonder if it would work on a vampire if they willfully chose to be a vampire (probably not or just a tiny amount).