Yeah, Zero is Pein. And, since it is spelled "Pein", lets go with that. He isn't the character from Final Fantasy X-2.Originally Posted by Id3aLiStiC
I just would also like to add another possibility to disprove the "Kakashi gained MS from guilt about getting Obito killed theory". Even if Kakashi's supposed guilt resulting from killing his best friend could awaken Mangekyou, there is also the question of who is truly his best friend. We know that Kakashi honors Obito as a soldier, and respects his final gift - judging by how he relies on Sharingan, and the change in his personality and tardiness after Kakashi Gaiden. However, I'd like to point out that Kakashi never liked Obito until just before his death; so I see at least a slim possiblity that - while he certainly respects him - Kakshi never considered Obito to be his single best friend.
In other words, Kakashi may have gained Mangekyou from killing another character, or may even have found another route to discovering MS. (I know I've elaborated on this idea multiple times before, but as it is regularly ignored, I felt I should point it out again.)
In any case, we should probably drop the whole argument....it's tiresome, and has never once led to any real certainty.