there's been a lot of theories about this from he's a spirit to he's part robot. I think that he is actually what he says i think that he is just a man but he's a man who's parents were killed in front of him when he was very young and because of this he trained, he trained all of his life to have revenge on the thing he blames for his parents murders, bending. He has trained so hard that he can move more fluidly than any other human alive and has mastered the ability to remove bending completely, just my thoughts but i think that amon is a complete bad ass and i would love for this to be the reason

HOLY SHIT IF YOU'RE RIGHT AMON IS BATMAN.

I think Amon has some sort of chi-control power. It would explain a lot of things.

I'm not too sure, but Katara managed to resist Hama's blood bending because she was stronger than her. Maybe he resisted it because he's hella strong?

I was thinking the same thing when Aang was under control to blood bending. Then I had the same reaction to this same scene. Amon is obviously a very strong character and there is a lot of explaining that needs to be done.

That could be true, but in order for that to work he would have to be stronger than all other benders in the show, as you know his father incapacitated Ang and everyone else all at once with easily.