http://uesp.net/wiki/Arena:Argonian#Argonian
WAIT, was I right about this. I said it may be due to evolution... it was 1000 years in the past. Maybe the evolved to have tails.

I mean an alliance between the Dunmer, Argoninans, and Nords? What the Hell? The Argonians don't have tails? That's like Burger king without whoppers.. Does the company who's making this has any "real" knowledge of the lore?
IF you about to be wiped out, you'll create an alliance with your most hated enemy if it serves to create a greater good. It doesn't mean they like each other.
I also wonder how they are going to rationalize how there were this many notable heroes running around during the Second Era and yet, miraculously, we've somehow never heard of any of them.
I would say it more akin to a war, sometimes people stand out... but a vast majority of people you will never know there name. Just because in the Single Player TES games your a hero, doesn't mean you be a hero in the MMO, rather a character that existed in the world.