Tav is a Paladin or Cleric that recognizes that Astarion is a vampire right away and drives him away from the group instead of recruiting him. Since this makes Astarion useless to the Emperor, his protection is withdrawn. Astarion feels the Absolute start to take hold of him, and he's screaming in horror in his mind about becoming a slave to a new master, when suddenly the control releases him.
Raphael appears and makes a deal with him to cure him of the tadpole. Astarion has to serve him as an assassin and a bed slave. And he'll send him after Cazador if he's *very* good.
Raphael wants to stop Cazador's ascension so that all those souls don't go to his father. He plans to put Astarion in Cazador's place, collect those souls himself, and have a powerful ascended vampire as his servant. But he needs to deal with the Absolute threat first, so in the meantime he might as well use Astarion as a cockwarmer.
Story to include Astarion and Haarlep rivalry. Friendship between Astarion and Hope. Astarion helping prevent Tav and Co from stealing the Orphic Hammer. And sex that swings wildly between soul shredding pleasure and mind rending pain.