Summary of ideas and concepts of the Fighters Guild, that were placed on the Old Forum.
Best summary is given by Rats in this Topic http://tamriel-rebuilt.org/old_forum/viewtopic.php?t=24673
The Imperial Guild of Fighters
”In the 283rd year of the 2nd Era, Potentate Versidue-Shaie was faced with a disintegrating empire. The vassal kingdoms throughout Tamriel had reached a new height of rebellion, openly challenging his rule. They refused his taxes and led sorties against the Imperial garrisons throughout the land. [...] [A] kinsman of Versidue-Shaie, Dinieras-Ves, "The Iron," presented himself with a host of companions before the Potentate. It was he who suggested an order of mercantile warriors-for-hire, who could be hired by nobility in lieu of a standing army. The employment would be temporary, and a percentage of their fees would go to the Potentate's government, thus putting salve on two of Versidue-Shaie greatest pains. Though it was then called The Syffim, after the Tsaesci word for "soldier," the organization that was to be known as the Fighters Guild had been born.” -- from the book ”History of the Fighters Guild”
”The Fighters Guild is a professional organization chartered by the Emperor to regulate the hiring and training of mercenaries. Training, goods, and services are cheaper for members, and the Guild Stewards know where to find work.”
-- Caius Cosades, a Blade master
”Your Guild merely continues the tradition of foreign occupation brought to this continent by the Tsaesci snakes. That is how my father and the other nobles see you. A foreign invader. That is your burden. Never forget it, shieldbearer of serpents.”
-- Surol Volayn, a local
”As a member of the Fighters Guild, you'll be around when things start getting dirty here in Vvardenfell. Stick with us. We're going places.”
-- Sjoring Hard-Heart, a Guild Steward
The Fighters Guild in Morrowind.
Like all the other Imperial Guilds in Morrowind, the Fighters Guild has traditionally been greeted with opposition from the natives, but thanks to the Empire's tiny renaissance after the end of the Simulacrum (that is: getting the right man to sit on the throne again) it has managed to gain a significant foothold in the province. House Hlaalu and other seemingly Empire-minded Dark Elves view the Guild as a useful business partner and its mercenaries a valuable asset, whereas the more conservative Dunmer – House Indoril in particular – are more openly hostile towards the Guild's presence, seeing it more as a force of foreign occupation, unwilling to look past its Akaviri roots.
The current situation.
The Fighters Guild, like the Empire it serves, is now faced with a looming collapse. The Guild has managed relatively well in the province of Morrowind, but only now the reasons behind their success are being unearthed. Though officially under the control of the Guild's leadership in Cyrodiil and the Imperial Council, the Guild is gradually becoming a thrall of the Camonna Tong, the native crime syndicate of Morrowind. Behind the scenes the Guild has slowly divided into two: those who are in the Tong's pocket and those who aren't (and aren't even that aware of the situation). These two opposing forces will have to collide before the Camonna Tong issue can be resolved.
In addition to the part external threat (and part internal threat) posed by the Camonna Tong corruption, the Guild faces trying times with its current leader. Grandmaster Joccathe of Bladed-Hymnals has recently left the guild headquarters in Old Ebonheart for a retreat of meditation in an undisclosed cavern somewhere within the vast Velothi Mountains. Bit of a philosophical warrior-monk, she's become more and more doubtful of the Guild's purpose to be present in Morrowind, thinking that perhaps the province and the land would be better off without the 'heirs' of an Akaviri fighting force walking their streets. In short, she's questioning the Empire and its colonization of Morrowind all in all. Her dwelling upon the Guild's ancient roots, the ethics of being foreign fighters in a foreign land and all things spiritiual and philosophical have left her blind to see that the Guild is evolving without her – to a bunch of Camonna Tong henchmen. This corrupted side of the guild is represented most strongly by the Narsis chapter of the Guild, directly and utterly under the Tong's control, led by the local Guild Steward Coraxes Myro. Myro comes from a long line of Colovian mercenary-warlords who believes that the Guild should embrace what they are: sellswords whose swords belong with whoever is winning and pays the most – the Tong. Since Joccathe's departure Myro has more or less seized power over the whole guild in Morrowind, with the exceptions of the guildhalls located in Imperial-controlled cities of Helnim, Firewatch, and Old Ebonheart; and the less-prominent halls such as Akamora and Ald'ruhn.
The player's part / the plot.
The player's role in all this is to uncover the truth behind the Guild's corruption and use this information the way the player sees fit. On the other hand, the dirty and violent path of joining the Camonna Tong and Steward Coraxes Myro would seem like the only way the Guild could persevere in a province that's otherwise traditionally opposed to it: by severing its ties to the Empire and start working against it (against the Thieves Guild, the abolitionists, the enemies of House Hlaalu). This will be the 'dark side' choice and it will not end well for the Guild. Alternatively there's the choice of siding with Joccathe. The player would then root out the Camonna Tong corruption but would then be left with an empty shell of a Guild, many of its members lost the Camonna Tong and a grandmaster who's lost her faith in the Empire and the Guild and their mission altogether. Of these two paths the player would choose the 'lesser evil', both leaving a bitter sweet feeling and a faint sense of impending doom for the Empire and its Guilds.
Relation the the Thieves Guild.
Yes, choosing the 'dark side' and joining with Coraxes Myro and the TC would lead to an open conflict with the Thieves Guild. Being successful in these end-game missions the player would be required to hunt down and kill key members of the Thieves Guild. This would make it impossible for the player to complete the Thieves Guild main questline. However, this would be A) just one of the two paths the player can take during the FG questline, B) made perfectly clear to the player before making such a heavy choice, C) done in a way that the player can 'fail' the quests by not killing them.
A quick list of Guildhalls and their Stewards in Morrowind
Ald'ruhn -- Persius Mercius -- vanilla
Balmora -- Eydis Fire-Eye -- vanilla
Vivec -- Sjoring Hard-Heart -- vanilla
Sadrith Mora -- Hrundi -- vanilla
Akamora -- Laalalvo Irano -- exists
Firewatch -- Galen Brandt -- exists
Helnim -- Hartise -- exists
Old Ebonheart (HQ) -- Joccathe of Bladed-Hymnals -- planning
Narsis -- Coraxes Myro -- planning
Almalexia -- ???? -- proposed guildhall
Baan Malur -- ???? -- proposed guildhall
Kogotél -- ???? -- proposed guildhall
Silnim -- ???? -- proposed guildhall
Kragenmoor -- ???? -- proposed guildhall