Until recently, the Dominion was unquestionably the only real power in the Gamma Quadrant. Governed by the Changlings, it ruled numerous systems with an iron hand - or limb of choice given the physical nature of its master race. Only after war with the Federation/Klingon/Romulan alliance did it suffer its first defeat and change its ways.
The founding race of the Dominion, sometimes called the "Founders," sometimes “What the hell did I just step in!?”are the Changlings. Most reside in an ocean-like mass on their homeworld known as "The Great Link." It is uncertain how a race of shapeshifters came to be. Rouge historian Well Redd theorized the Gamma Quadrant once had a race governed by master politicians who became so expert at shifting their political opinions to fit the political environment, that they eventually gained the ability to change the form of their bodies as well. The Founders claim that once they began exploring beyond their world, they encountered hostility everywhere they went (perhaps reflecting the nature of the peoples' distrust of slick politicians).
To the Changlings' credit, they did seem to make an effort to discover if there were any peaceable races out there. And so about a hundred capsules containing baby changlings in a state of suspended animation were sent out in all directions. Why send infants? Odo, who had been one of those sent out, had the idea, "What better way to judge a race than to see how it treats your most helpless members?" As it turned out, the Changling orphanage was overloaded, and them being politicians by nature, "it seemed like a good idea." Unfortunetly, simply sending capsules in random directions in empty space does not guarantee success, as that only Odo and a few others were ever heard from. Though there are rumors that some Changeling young may still be out there waiting to be found, much like abandoned minefields leftover after a war.
The Changlings decided all other "solids" were intrinsically hostile to them, and decided rather than hide, they would be the masters. They considered taking over some existing races to act as warriors and administrators (We all know that a politician will never subject him or her self to danger if they can avoid it, or leave their offices for that matter), but this was thought to be too cost effective. Instead they embarked on a costly program of genetically engineering the most aggressive traits from 100 races into a solder. This took years and huge amounts of resources but finally they had their first batch of soldiers. They were hulking monsters that would make a Klingon wet himself just looking at one. However this first run proved less than successful, as they seemed just fine, till one checked between its legs and promptly flew into a rage. The Founders reproduce asexually and didn’t have a clue what was making their creation become so cranky. Isn’t cloning much better?
The genetics lab was eventually destroyed from orbit and the Founders set up hundreds of comities to study the problem of what went wrong. After many years of thought and thousands of pages of data, the comities admitted they hadn’t a clue. At this point the Founders considered giving up, but the program was such a money pit they just couldn’t bring themselves to scrap it.
The answer of control came to them while discussing a bill limiting what could or could not be said in mass media. (They had no mass media as construction had been halted over a thousand years ago when the bill first came up) Historical records showed that people would become addicted to such material, doing almost anything to maintain their supply. Would this not work for their creations? They rebuilt the labs and reproduced the work at great cost, wrecking the plans of the “Beatification of the Link” subcommittee and several others (Now you know why they live in a hole in the ground).
The results were the Vorta and the Jem-Hadar. They seemed to be just what the Founders wanted. Fanatically loyal to them and willing to do anything to keep their supply of daytime TV coming. The TVs however proved to be a liability as when the Jem-Hadar went into battle they would withdraw as soon as reception became unreliable, and they would stop at any water cooler to discuss what they had seen. They also tended to stop what they were doing during the exciting bits.
A bright Founder went to back to the records and looked for something other than TV they could use, and finally found drugs. Drugs had always been a good political weapon for them in the past. Why not make it part of their true weapons systems? So they developed a drug they dubbed “Ketresel White.” This drug made their creations totally devoted to their Founder pushers. (Analysis of the chemical showed it to be made up of a combination of cocaine, morphine, nicotine, caffeine, and endorphins similar to those produced while playing "Everquest", "No wonder they wouldn't risk disappointing the ones providing the drug!")
With this addition the weapons were complete. Both of these races were gender-neutral as the first warriors had been, and reproduced only through cloning, "The only fun they had was terrorizing other races and getting smashed so they wouldn’t think about the fact they were gender neutral."
The Jem-Hadar were the enforcers of the Founders' will, seemingly fanatically loyal to their masters to the point of willing to commit suicidal attacks and slaugher without question (Wouldn’t you rather die or kill rather than know you had to go through life neutered?). The Vorta were the Founders "middle management," serving as directors of Jem-Hadar troop movements, planetary governors, and negotiators. The latter job was often simple as it was simply a demand to comply with the Dominion or die. Humanoid, the Vorta have stated they were not simply created from scratch, but from the genetic code of some Gamma Quadrant primate (leading some to joke behind their backs they're always up to monkey business). Although they can eat, they have no sense of taste, and the structure of the "creative half" of the brain is less able to comprehend art and artistic tastes. Needless to say, Vorta make lousy gormets and art judges (They are however considered among the top art critics and TV producers the galaxy has produced). Those who have encountered Vorta usually describe them as haughty with an air of arrogance, seemingly more concerened with their own momentary comfort than even their own soldiers' lives. The rouge historian Redd suggested the Vorta were cloned from DNA samples of the politician ancestors of the Changlings, while others think the original DNA may have come from the designers of New Coke and the Edsel).
For years, the Dominion subjugated a number of systems in the Gamma Quadrant, any question of their rule answered with hordes of Jem-Hadar landing on the planet, shooting anything they could find. As none of the races in the area were burrowers or thought to build underground complexes, they soon began meekly obeying them. The situation continued for years, until the Founders became aware of the Federation and the Bajoran wormhole. Despite that a Changling had been acepted by the Federation and Bajorans, the Dominion considered them no less hostile than other "solids." Why they refused to accept circumstances had changed is less than clear, though rouge historian Redd thought, "Politicians tend to be the last to acknowledge new realities contrary to those they follow all their lives." (They also were in need of something for the Jem-Hadar to do rather than just sitting around getting blitzed and wondering why they had no attributes.)
From the begining, the Dominion never hid their distrust, which was worsened by a sneak attack by the Romulans and Cardassians which utterly failed (They forgot the wormhole was in Federation territory). As there was a Changling spy in the midst, they charged it had manipulated personel into making the bungled assault in the first place. Paranoia of a Changling plots did more damage than the Changlings themselves, notably the Klingons declaring war on the Cardassians and Federation (Many say they felt left out and just had to fight someone). Some also claim there was an attempted coup in the Federation by Starfleet officials fearing the democratic process made them open to attacks. But this is absolutely ludicrous as Starfleet personel would *never* do such a thing.
Irronically, the Klingon attack on the Cardassians on the grounds the changlings had infiltrated them led to the Cardassian Union making an alliance with the Dominion (One Klingon scholar was heard to say “See, see, we told you so!). Faced with either being next on the attack list or breaking their "don't fire first" policy, the Federation instead mined the wormhole to the Gamma Quadrant. The Dominion however did not appreciate this act of sublety and declared war on the Federation as well. Despite being cut off from home, the Dominion forces were getting the better of Federation forces. With redshirts having enough trouble surviving in peacetime, when faced with an actual war they found the situation often too much to bear.
The Dominion captured some important worlds when the Federation fell low on redshirts to throw at them, notably Betazed. How the planet of psionics was unable to forsee the invasion is unknown. They began making plans for long-term occupation, including the killing off of Earth's population by ordering their laundromats to wash shirts and pants seperately, and putting red dye into the ones for shirts. "Isn't that a little extreme?" "It's been the source of so many annoyances, humans, Starfleet, mimes ... " Then the Romulans entered the Federation-Klingon Alliance. This was due to a Romulan diplomat's death due to a Cardassian bomb blowing up his shuttle after a trip to the Federation to see supposed evidence of Dominion plans to conquer them after finishing the Klingons and Federation. The Dominion and Cardassians denied involvement, one of the latter suggesting the Federation had Cardassian sympathisers do it. But no one believed him as the Federation would never stoop to such Malachevian tactics.
Thanks to Romulan reinforcments and some daring strikes into Dominion-held territory, the Alliance gained the upper hand. Then the Dominion made an agreement with the Breen, a little-known race that have been compared to the Tholians in secrecy. Around other races, Breen always wear masks. Although it is generally attributed to their living on a polar planet, some say they're so ugly they got tired of heart attacks and cameras breaking, though they didn’t mind the occasional vomiting. They're also noted for their bodies having no blood, a physiological trait that tends to discourage attacks from more bloodthristy races, and thus not getting the attention of action-hungry Federation media.
The Breen's shield-penetrating weapons stopped Alliance counter-offensives, but only for a time. The Cardassians found themselves less as partners and more as "subjects who should be grateful for our benevolent rule." The result was rebellion. Despite all the Jem-Hadar and ships lost, what distressed the Vorta admistrator the most was the destruction of a small cloning facility in what gurellias thought was a simple distraction raid, "Oh no! I may be the last Weyoun clone ever."
Durring this time, the Founders themselves fell ill due to a virus, (though some say it was actually an expired egg salad sandwich one of them got from a vending machine). Some charged this was a deliberate attempt by the Federation's supposed secret organization "Section 31" to stop the Dominion by exterminating the Founders. But this was dismissed as there is no Section 31 and no Federation official would ever think commiting this kind of genocide no matter how bad things get.
In what seemed like an ironic replay of the Bajoran rebelion, the more the Dominion cracked down, the more the resistance grew. Finally the Alliance made a move to take Cardassia Prime. Thinking it would quiet things down, the Dominion razed a Cardassian city (unfortunately for them this city held the last manufacturing plant for Ketresel White on the planet reducing the Dominion forces to going door to door looking for their next fix). The result was the Cardassian forces changing sides, causing Dominion forces to crumble, and costing them the planet. Confronted by Federation forces breaking down her door, phasering the Jem-Hadar defenders and the Vorta, and capturing her, the Founder there responded, "You shouldn't have done that. That was the last Weyoun clone."
Although she defiantly stated they were capable of razing every planet they still held and commitng their remaining forces into kamakazie strikes, after a talk with Odo, the Founder gave in. A cease-fire was ordered, and a peace treaty was signed. The Dominion War was over.
Since Odo joined the "Great Link," curing them of the plauge, the Dominion has became much quieter in galactic affairs, no longer threatening others and easing it's once iron rule over it's subjects. The Dominion was finally at peace with the "solids" it once had no trust in, ableit after great numbers of men, material, and effort had been spent. For the Founders it was considered a job well done and is to this day is celebrated as a victory (remember they are politicians and no politician has ever lost a war if they still have a job at the end).
"Couldn't we have avoided all this if we had only let Odo into the Link when we met him?"
"Shut up!"
Special thanks to Saia for the suggestions