And I also think Karlach is not talking about the soul in the literally.
Sounds like a metaphor, not a literal description. The whole point of carving the scars on Cazador's back is precisely so Astarion doesn't lose his own soul. It's a trade and a loophole in the deal Cazador made with Mephisto.
Yes, I also think so.
Agreed, that's the first thing I thought when I read that line. It's like when someone says you "lose your soul" when you work a corporate job. I'm sure some people will make the argument that since in Faerun, souls are proven to be tangible things, she must have meant this literally, but I just don't buy that.
