Even 'if' sounds like a rather strong word in this particular instance. Vena's never really had reservations about what it is he has to do to survive. Nothing about taking advantage of people in their sleep or manipulating them when they're awake. Using his powers to practically brainwash people into loving him and obsessing over him. Being unable to live without him. Needing him so much it drives them insane. It's never bothered him that each time he has sex with someone, they grow closer and closer to death. He chips away at their mortal lives until there's nothing left.

But that's just it. It's a slow death. People may be able to recover from him eventually (physically, not emotionally or mentally. Few people ever get over their incubus) if he decides to simply leave them alone. Su-jin eats others. There is no coming back from that. There is no surviving that. Su-jin's feedings mean the end for anyone on the wrong side of it.

Unless the other person can't die in the first place.

"You will," Vena repeats. "Have you not figured out why we were chosen for one another?"