Not joinable, and only a few related quests.

Regional Grand Spymasters of the Blades (like Caius Cosades, who will be your 'handler') receive instructions directly from the Emperor. Within the Morrowind game, only the intelligence operations are experienced directly.

The Blades are the Emperor's elite espionage, military, and diplomacy service.

Joined automatically during the Main Quest.

Most such factions originate from Cyrodiil and have made their way to Vvardenfell. The Imperial factions are all establishments relating to Imperial traditions and politics. Neither House appears as a faction in the game. House Dres has no in-game impact on the province at all.

House Indoril is noted for making up a large percentage of Ordinators, and a member of House Indoril, Mehra Drora, can be found in Gnisis.

However, there is an exploitable bug which makes it possible to join Hlaalu and either Redoran or Telvanni.

You can (without cheating) usually only join one of the three Great Houses.

The Sixth House has mutual antipathy with most other factions in the game, and no allied factions. It recruits necromancers and mercenaries to take control of Daedric Shrines and other abandoned sites that can be defended, including underneath established cities.

Disgraced an age ago, and long thought to have been utterly destroyed, this ancient House is rebuilding itself and is allied directly with Dagoth Ur and the Daedra.Advancement to the higher ranks of the Telvanni requires impressive magic skills and intelligence. House Telvanni has come into conflict with the Mages Guild (below), for control of magic-related services and resources. An isolationist Great House led by a council of mages (not all of whom are exactly friendly to one another), the Telvanni are the Great House that is least accepting to outlanders of any kind.The Redoran, politics aside, have mutual respect for and from other warrior-caste groups, such as the Fighters Guild and the Imperial Legion (below). House Redoran has deep ties to the native culture, despite their civilized veneer. A Great House primarily of warriors, though with business interests that clash with those of House Hlaalu, the Redoran have an eye to reestablishing Morrowind's former, pre-Imperial glory, though they stop short of open revolt against the Empire.Everything is business to the Hlaalu, and the house is ultimately controlled by the Dunmer Hlaalu family, some of whom possess titles of Imperial nobility. The most Empire-friendly of the Great Houses in Morrowind, and the most focused on commerce and politics, House Hlaalu is also the easiest Great House on Vvardenfell to join and advance within for a non-Dunmer outlander (one of the top Hlaalu people in Morrowind is of Imperial stock).A fourth, House Indoril (not covered below, as it is not coded as a faction in Morrowind), supplies the majority of the Ordinators. Of the Empire's five recognized Great Houses, only three have a governing and commerce presence on the island of Vvardenfell in particular. The Great Houses' traditions derive from ancient Dunmer clans and tribes, but they now function something like political parties. The Great Houses are the large establishments, throughout the Morrowind province, of extended lineages of 'civilized' Dunmer, with many non-Dunmer retainers (and sometimes officers).

Blade and soul change faction