To start off with this topic i have some info from uesp.net if you have any specific questions regarding Blacklight
This we know: Blacklight was a major Redoran city on the northwestern coast of Mainland Morrowind close to the border of Skyrim.
To the south are the western highlands and a good road west connects through the Dunmeth pass to Windhelm.
History:
Tiber Septim used Blacklight as a staging ground due to the weak Dunmer defenses here.
Architecture:
Typical Dunmer Craftsmenship with Nord influences
Current events/speculation:
As soon as the Red Mountain blew its top the Argonians of Black Marsh invaded Morrowind beating the vulnerable Dunmer. Most of the Dunmer retreted to Solsthiem.
(The rest of this is all Speculation)
The Dunmer regain their Stength in Solsthiem and a united Morrowind Government Stage an assult on the Argonian held city of Blacklight. They retake the city but suffer major casultys. The Argonians retreat south in the Western Highlands and set up camp there. The Dunmer face new challeges trying to hold the city of Blacklight and also an impending counter attack by the Argonians but they need the help of an outsider to help Blacklights Residents, Economy, Government, and Defenses and Eventually drive the Argonians out of the western highlands.

Sounds cool, but only if you can choose to help either side achieve victory... What if I'm playing an Argonian, I'm not gonna help slave trading arseholes against my own kind.

Long as I get to kill argonians, sure.

If we aren't able to choose which side we want, then it isn't worth it. Although, we should be able to change sides whenever we want (up to a certain point in the expansions MQ) with a small penalty, for 'spy' type characters. Also, the side we choose should have far greater reaching penalties than just the 'everyone in this town is now dunmer instead of argonian' gimmick.

I want Morrowind in Skyrim so bad I'll accept it in any way.

:spotted owl:

Sounds like a nice idea, like everyone else here I'd like to see it happening, though most chances it won't.
Thing is, what gives you the right to intervene in this war, you're a -complete- outsider, I can't see a reason for you to walk right into this war with an excuse of "helping".

Well you could extend that to damn near anything a hero intervenes with. Lets face it, heroes are pretty much the ultimate in nosy-busybodies they don't need a legit reason to be involved beyond wanting to be.

Well... if it's going to be like "Hey, you! we need your help, I know you're a complete stranger and I have no connection to real life or whatever, but we need any help we can get, even if you're a pedophile that may molest our children and kill their parents, deal? =D" then I won't like this idea... I'm kinda tired of these kinds of ways to make you intervene in a certain quest... What I would like to see is something that actually connects you to this situation.

I really don't see the Argonians pushing that far north into Morrowind. If any region would have been occupied perhaps the just the Southern region up to the Deshaan Plains around the Narsis (Mainly controlled by House Dres, a major player in the slave trade from Blackmarsh). The remainder would have been nothing more than complete wasteland. Remember that the Western regions near to Morrowind could remain unscathed because of the Velothi Mountains... Blacklight could be nothing more than cinders, yet cities such as Windhelm and Riften completely untouched by the devastation.

This is not me saying I don't like your proposal, just seems illogical from a point of military, social or psychological perspective.

But it would be interesting to see some play into the successful return of the Dunmer as an expansion. After all they have suffered so much betrayal; Azura, Neravar and Dumac, the Tribunal, the interim struggle between Vuhon and Sul to oppose the descent of the Ministry, etc. But this begs the question, yes? Where could Bethesda go with it? Solstheim has been done. Could anything be done to restore Morrowind to its former glory? Another realm of a Daedric Prince to be visited (*cough* Moonshadow *cough* expansion)?

I'd rather see High Rock.

It seems as though the Argonians may have pushed this far north. Why would the Dunmer and Redoran to be specific retreat as far north as Solsthiem. The Redoran even are a Warrior based clan and they got pushed into Solsthiem. Also it seems as though the Volcano may have only destroyed Vvardenfell. Military wise it does make since that the Argonians would push this far why else would they go as far as Solsthiem. This Area of Morrowind hasn't been covered and i would love to traverse between Windhelm and Blacklight. Bethesda could also twist the plot into whatever they please I was just merly guessing the plot.

Also to commet the posts Above I don't believe you should choose sides in a major plot in a TES game because of the History and Lore of the Region