Stiff animation. Not a fan of this style. "Friend"? Feels like tumblr fan-fic. Why such blunt narrative exhibition? It's as if the writers think that simply stating something directly makes it so, without backing it up with detail. I'd argue that it's way more reasonable to see them as two instruments of war that slowly realise that they weren't actually enemies. Thel, because he was lied to, and John cause he realises that Thel was lied to. Having them already be friends at Halo 3 feels cheap and rushed. They'd need another arc (no pun intended) for that. Halo 3 was learning to fight alongside a previous foe. It also feels undeserved cause we never actually heard John call Thel friend. Assuming that it happened behind the scenes--- I'm not even going to bother explaining why that's low quality storytelling, other than to say that if "friend" has any weight, it ought to be highlighted.

If you think about it, John and Thel didn't really have much interaction. Sure, they were both playable in Halo 2 and co-operatively in Halo 3, but they didn't spend all that much time together. John probably doesn't know what Thel did before they met, at least not in detail.

Well he's slaughtered plenty of other elites before in Cole Protocol. He seemed very violent from what i recall. Not only that but hes been in the destruction of countless human worlds and has taken who knows how many human lives.