While this could work in vanilla Morrowind because of the very limited amount of politics involved in the major questlines, this would feel rather awkward in TR, especially with factions with clashing views.
I think that the first thing that needs to be done is a list of all the joinable factions that will be in TR. Right now, there will be:
[spoiler]- House Indoril
- House Dres
- House Hlaalu
- House Redoran
- House Telvanni
- The Temple
- The Morag Tong
- The Blades (but since they remain secret and part of the main quest, they shouldn't clash with any other faction)
- The Imperial Cult
- The Imperial Archeological Society
- The Imperial Legion
- The East Empire Company
- The Fighters Guild
- The Mages Guild
- The Thieves Guild
- The Vampire Clans (their relations with other factions are more conditioned by them being vampires than by them being part of this or that clan, so I count them as one)[/spoiler]
That said, and keeping in mind there probably shouldn't be too many joinable factions either, I'd like to add two more to that list: the Camonna Tong and the Twin Lamps. Currently, the Camonna Tong is being limited to a sub-faction of House Hlaalu, and the Twin Lamps haven't been expanded upon.
However, I believe these two factions should be joinable outside of House Hlaalu, as their actions clearly affect more the province than the House itself. The Camonna Tong is the official mafia of Morrowind. It'd be odd to have it joinable only if the player is part of the most pro-Imperial-in-appearance House of Morrowind, while you could very easily see a Dres or a Telvanni being part of the Tong.
The Twin Lamps are a large anti-slavery movement, aiming to fight against the pro-slavery factions and to free as many slaves as possible. Moreover, they currently aren't very linked to House Hlaalu (their quests can be completed in spite of the house affiliation), and could easily fit with, say, a non-aligned Khajiit thieve.
Finally, they would be two additional secret organisations, alongside with the Thieves Guild and kind of the Morag Tong. They would also help a lot in defining the player's choices and ideals, emphasizing the roleplay aspect of the game.
Now, for realistic purposes, I believe we should also make a list of mutually exclusive factions, including the Camonna Tong and the Twin Lamps.
This is what I'd propose:
- The Imperial Cult and the Temple: for obvious reasons, one cannot be the head of two different religions. I actually believe the Imperial Cult questline should turn around trying to convert the Dunmeri people.
- The Imperial Cult and House Indoril: again, for obvious reasons, the most pious House would not accept in its ranks an outlander with heretic beliefs. On the other hand, I think it'd be interesting to have House Indoril force the player to join the Temple. That way, the player would show that he has indeed abandoned all his outlander roots, and fully embraced the Dunmeri culture.
- The Camonna Tong/House Dres and the Twin Lamps: the Camonna Tong and House Dres are two pro-slavery factions that would actually need the player to endorse slavery, thus making it impossible to join the anti-slavery movement. On the other hand, House Telvanni is generally pro-slavery, but its members are so independent that they shouldn't necessarily have to conform to the majority's opinion. House Hlaalu already hosts the Twin Lamps and is rather moderate on that issue, much like the Indoril should be IMO. Concerning the Redoran, I'm not even sure they use slaves.
- The Thieves Guild and the Camonna Tong: being two secret rival organisations, with different views, backgrounds and clashing questlines, joining one of the factions would lead to trying to dismantle the other.
- The Imperial Legion and Houses Indoril/Dres: These two houses being the most vocally anti-Imperial houses of Morrowind, and the Imperial Legion being the physical embodiment of the Imperial rule, these factions should be incompatible.
That's all I have for now, I might add some things later. I don't want the Camonna Tong to be too incompatible with Imperial factions, as it remains a secret organisation and these Imperial factions shouldn't know about you being with them. The Camonna Tong might also believe it to be good to have a spy inside the "Imperial system".
This is a topic for discussion and debate, and I'm just making a proposal. I think working on this would definitely help improve the actual place of politics in Morrowind as well as the roleplay aspect of the game
PS: I wanted to post this in Master Planning, but I don't have the permission to do so. I hope it won't be a problem if I post this here.
PS 2: I haven't played in any Vampire clan, so I'm not sure how the game manages the faction incompatibilities on that one. I guess they'd pretty much be incompatible with everyone because they're simply unable to talk with any faction, except for the Mages Guild and Houses Telvanni and Dres.