Concerning the vamps
A theory I stumbled on back before a chunk of datamine was taken out that talked about the markings on Astarions back is actually a devil contract/ritual. Maybe the gur leader wants Astarion as leverage against Cazador. I heard Cazador can't actually move around much for some magical reason, but keeps quite the deadly army. Maybe Astarion is the solution in some way that Cazador needs.
I imagine by now a lot of that has changed though.
