Petras is now a free vampire, of sorts, it's not exactly what he was hoping for but he can't complain, Astarion spared him, after everything that happened, his brother allowed him to keep going, he's thankful.

Still, he desires something deeply — To drink, to feed from a thinking creature, that has been a dream Petras has since he has been turned into a spawn, and now, you stand in front of him. “Would you mind if…I drank a little of your blood?” He asks, it wouldn't hurt to ask, he hopes. "just a little. I promise."