I think that it's a clever idea that gives your PC a whole other narrative string to deal with without committing to a locked in race/class like the other origins.
Unfortunately, I'm not really interested in playing as a serial killer with some kind of pathological illness, so I'll probably never use it. I kind of wish there were additional non-companion origins to explore. Ones that are less grimdark.
You are making assumptions. It seems very likely to me that the character’s illness is magical and connected to Bhaal, not pathological.
