As it is a big part on roleplaying I dug into the lore again to find some more specific facts about Great House Telvanni.
Fact 1: there is little knowledge about the Great House's endeavours during the 2nd Era. We know that Port Telvannis had been sacked ten years ago by Akaviri forces, which likely meant that many Telvanni emigrated to Vvardenfell and the mainland of Morrowind.
The Telvanni you meet in the game are a little arrogant but they take care of matters at hand, confining the crisis at the best of their abilities.
Fact 2: In the Third Era the Telvanni spent more time fighting each other in bloody vendettas than fighting the other houses. In fact Great House Telvanni joined forces with the Hlaalu to topple the Mages Guild later in history, so their hate for the other Houses can't be deeper than their disdain for these outlandish wannabes. But as there is also a Telvanni mage somewhere in a Mages Guild facility, they clearly work with these fetchers to avert this nasty planemeld.
Fact 3: Great House Telvanni didn't join the Ebonheart Pact, but Morrowind is still their home though the other Great Houses run the show.
Fact 4: Relating to Third Era knowledge the Telvanni councilors are so very uninterested in politics, that they sent their Mouths to council meetings. Some of them care so little that they don't even know who is Archmagister at the moment.
Conclusions:
- Great House Telvanni is still recovering from a major blow against their haven. Likely the worst setback they have ever experienced. Ten years later everything has been rebuilt, but resources, many unique artifacts and assets are still lost.
- Great House Telvanni didn't join the pact, but they certainly are pulling strings, which can't be achieved by being hostile against everybody.
- Telvannis are convinced they are superior, which they have proven time and time again. One example for this is the Heimlyn Keep vault.
- We like House Hlaalu more than the Mages Guild.
- The crisis at hand and the battered state of the Great House Telvanni, plus reduced to pulling strings without actually ruling anything in Morrowind, leaves little room for their bloody vendettas which will follow later in history.
- Outlanders are worse than Dunmer. Even than the Dres.
Some sources:
http://www.uesp.net/wiki/Lore:Great_Houses
http://www.uesp.net/wiki/Lore:House_Telvanni
http://elderscrolls.wikia.com/wiki/House_Telvanni
