I know of Madmitten, and he's cool and all.
Never heard of Athey123. Know nothing of any hatred between the two.
If anything, this sounds more like you are/know Athey in-game and don't like Madmitten.
Unless of course you can give us a link to his profile.
Athey123 is a dumbass. I agree with madmitten. I played some games with him and he was a complete dumbass