Well this may be sloppy because I'm typing it from a mobile device but...
I also know the lore very well and so do many others. In fact in the lore forum here we came to a consensus that it is actually NOT stepping on the lore. It's fine that you don't think it's lore friendly but you should support your claims if you want to be taken seriously. Enemies have worked together before. Even the worst of them. Sparta and Athens worked together against the Persians and they hated one another. Germans collaborated with the Japanese in WWII and they would have incredibly different outlooks and both were both rather radical purists.
The Nords even have worked with the Dunmer before. I think you have preconceived notions of how the races would have acted but not a whole lot to support those notions. Not all the Dunmer are racist slave owners and not all the Nords are Mer killing beer swilling barbarian warriors.
You are underestimating practicality. You would be very surprised by what normal people will turn to when they are desperate enough. You and no one else including me truly knows how people in Tamriel thought back then either. With the growing pressure from the newly formed Aldmeri Dominion and Daggerfall Covenant as well as the chaos brewing in Cyrodiil with their Imperial kin falling under the power of the machinations of a Masterfull Necromancer and a Daedric Prince. In desperation where would they turn if the Daggerfall Covenant wasn't interested or only wanted their surrender? They may not get along famously with the Dunmer but there is nothing to suggest they would not work together begrudgingly.
It is not really that incredulous, and I am a hardcoe Nord and Dunmer fan, well aware of how they view one another. However even recent views when taken into account are promising. The Nords took in the Dunmer refugees and did not interfere with their claimant of Solstheim in the 4th Era. The most recent views of the Nords as true Mer haters in Skyrim is mostly due to recent events and the Thalmor as well as the whole thing with the Falmer. Even that has things that excuse the Nords hatred of Mer, initially they got along with the Falmer but then the Eye of Magnus was discovered and the Night of Tears happened. They even respectfully buried the leader of hte Falmer, the Snow Prince in a gesture of respect.
In the past the Dunmer and Nords respected one another even when they did hate each other in the various wars and disputes they have had. They are not far fetched.
Now here's where it is touchy ground. The Argonians. We simply need more info than we have. But going off what I know I will try to explain. As far as I know at the time the MMO is taking place is a rather bad time for Black Marsh. There are hordes of Bandits and Pirates everywhere and Imperial Warlords are scattered throughout the province ruling the old pre-Potentate Empire's old holdings. How organized the Argonians are at this point is unknown. There was a major spike in slaves at this time I believe. We know the Argonians sold their own into slavery and similar to the various rival tribes in Africa most of the actual slave nabbing was done by locals like the Archeins. Here is something interesting.
Archeins: During the era when other races tried to put plantations in Argonia, Archeins were very powerful, and made fortunes by selling other Argonians into slavery. Since the other races realized Argonia is unfit for plantations, they have gone bankrupt.
This could mean the Archeins are in control and are on very friendly terms with the Dunmer for the purpose of selling slaves. I think that Black Marsh is a bit of a Kleptocracy during this period and even until later in the 3rd Era. Of interest is the http://www.uesp.net/wiki/Lore:The_Argonian_Account
Now if this is the case or even if it is not, the Argonians need protection from the Dunmer slaving interests and the growing threats of the other powers as well as the whole Molag Bal and Mannimarco thing with the Imperials. The way they are getting there protection from the Dunmer might be that they intend for this alliance to improve the relations with the Dunmer and possibly convince the Dunmer they are not lesser beings. It also is worth mentioning that the Dunmer and Nords supposedly approached the Argonians after working out their own deal. When two peoples that consider your people to be inferior ask for your help when you need it, you kind of feel a need to prove yourself and them wrong. Just working a theory here. It is also possible the Hist, Greybeards and the Tribunal had some fun kind of commute and that netted them a necessary if unstable alliance with old hatreds by nature being a common problem and those problems commonly rearing their ugly little heads.
» Mon May 14, 2012 2:41 pm 
But, this isn't just some outside studio that acquired the rights to do a TES MMO. They're all operating under the same umbrella, so I would imagine there is a common interest to make the best out of it and do the name 'The Elder Scrolls' justice. I think you just need to have a little faith that it's really not as gloomy as you think it is or will be.
