Quote Originally Posted by Falbrogna View Post
Because it's interesting and serves the story's purposes. 'nuff said.
That's begging the question. What story purpose does it serve? What benefit would there be to showing us one standard form of vampirization, then bringing in something that looks a lot like a second standard form of vampirization (but secretly isn't) and applying it to the same character? What purpose could there be in not giving the audience an explanation for this complicated vamped-and-possessed situation for Durkon you're proposing? One line of dialogue? Some kind of hint?

That's not a third thing the same as someone casting Magic Jar on someone else doesn't make it "a third way to be born".
There's vampires, and there's Hel's spirits who can possess undeads/people. Durkon isn't being "corrupted" because he's been driven to the back seat and can't feel anything about his new condition.
It's that simple.
From the audience's point of view, if you're correct, then what's happening to Durkon is not what happens to most vampires. That's a layer of complication that would require some attention and explanation, if it were true.

This very thread proves that the answer is no.
We're never going to get 100% buy-in for any explanation. There will always be one or two lone holdouts. As far as I'm concerned, the question is settled.