[quote=Spawnling]
What I mean is that I really REALLY REALLY don't think there's any plausible way for him to survive staking in the heart, neither side of his race has immunity to that. It's one of the cornerstone ways to kill both a vampire and a human, there's no reason for him to suddenly be immune to it.
[/quote]

I'm taking a cue from a couple of my inspirational sources. Essentially what happens is that both sides cancel each other out. The human side removes the symbolic insta-kill weakness of the heart. The vampire side keeps the human side from dying without a heart by focusing all of its regenerative efforts on keeping him alive without a beating heart. If he isn't blood-empowered when he's staked, he'll be rendered comatose from the effort.