Board Thread:Questions and Answers/@comment-4495539-20140531082603/@comment-3298453-20141025053836

I think it's Kenny. He was so intent on getting Ben and Kai together (to protect his own existance, of course). And he almost called Ben "dad". And he was in Ben's house in the end of the episode, and it can't be easy to get into Ben 10,000's house unless you live there or something. And he got the black orb thing for Kai, because he knew it would make her happy. So he's got to be Kenny.