If Astarion were Cazador, then the PC automatically would become a vampire spawn, If they let Astarion feed.
Maiden Fel sounds like one of the sisters of Ethel, If you take the classical witch coven: Ethel is the crone, Fel the maiden and then there is the mother. Not sure If that make sense and what a hag would want with a vampire spawn, so probably just another crazy theory.
"We are all stories in the end. Just make it a good one."
