[Mettaton looks uncomfortable at that. He sort of draws into himself, his legs pulling in close and his arms wrapping loosely around them.]

He had the Royal Guard for that. But...monsters aren't inherently violent. Not to that extent. Maybe Undyne...but. I was alright with it. With the idea of hurting humans.

[His tone and backpedaling makes it clear that at this point, he's fishing for justification.

But then he says something that...really, in his mind, is irredeemable at this point. He hides it, he pushes it away and says "that's not me anymore" to himself. But it's ugly, even as he says it.]

Did you know I almost killed someone on the ship once? Frisk. I almost killed them.