I'm trying to mess with cannibalism and vampirism a bit, I noticed the perks call Player.StartCannibalism() and Player.StartVampireFeed() and I can't find these anywhere in the vampire/cannibalism scripts

These are native functions of actors. They're listed in the actor script and http://www.creationkit.com/Actor_Script

What is a native function?

Native probably means that they are not custom scripted? Not sure, I'm still reading the Wiki.

Apparently native functions are defined in game engine http://www.creationkit.com/Scripting_Tutorial_Using_Functions#Native_Functions
Meaning there's no chance of seeing whats happening. Does anybody know how to set the eaten flag? (HasBeenEaten)