I would love the Betazoids to have been drastically changed by their life under the Dominion. Maybe they're all going through a Lon Suder moment but this idea of a once peaceful telepathic Federation member now turned malevolent causing trouble would be an interesting storyline.
I had this idea once about the Betazoids being distrusted by the Post Dominon-War Federation and treated as pariahs because their occupation was "cosy" (meaning there was minimal/negligible or even no loss of life or destruction both during the fall of the planet or during the time they were occupied, as opposed to places like Benzar, where there was considerable fighting)
That's because the Dominon hand-picked Betazed as their beachhead in Federation space precisely because it had a civilization of telepaths and they knew how to control those with minimal effort, both to save resources and to use the planet as a propaganda tool to other Alpha Quadrant worlds "submit and we will be good and merciful overlords!"
What actually happened was that during the fall of the planet, the Vorta commanding the Dominion forces agreed to meet with the Betazoid leaders (who'd naturally attempt to negotiate their way out of the situation as their plan a)
Said Vorta, probably a new incarnation of Kilana, or someone similar to her, chosen exactly because the Betazoids would react positively to her, was a kind of Trojan Horse, carrying a sort of engineered telepathic virus or parasite that would spread to the minds of the leaders as they tried to "read" her and from them to the rest of the population.
Night impossible to detect this virus/parasite would not take-over the Betazoids or anything "coarse" like that...but instead it would subtly and insidiously alter them to become the perfect, obedient subjects by altering the way they experience fear to put them into a constant state of blank terror. Those that were strong enough to overcome that mental conditioning would encounter the second stage of that mental infection; finding their mind overcome with graphic images of what happened to species in the Gamma Quadrant that rebelled against the Dominon, of what would happen to them, to their loved ones, to their world if they resisted. And those Betazoids who overcame even this second stage and still wanted to fight back...well those are the ones who'd account for the "negligible causalities" mentioned earlier.
So for their whole occupation the Betazoids would find themselves forced into lockstep by that terror virus/parasite and would comply with whatever the Dominon demanded of them, including aiding their attacks on other Federation worlds with supplies and the repair of ships. Any resistance was extremely limited, short lived and ineffectual.
A "vaccine" for the virus/parasite might have been negotiated as part of the reparations the Dominion was obliged to provide, but the mental scars from living in mortal fear for so long would remain, causing a change in the behaviour of the whole species to be, among other things more guarded, suspicious and nervous.
Or, since the parasite/virus is hardly detectable, the Dominon might never reveal what they did and it would take considerable time after the war to discover and counteract it.
I can imagine a good number of non-telepathic species would dismiss the severity of what was done to the minds of the Betazoids "So they frightened you? We were frightened too, and we still fought back!" Especially planets who were the targets of Dominion attacks launched from Betazed would be particularly unforgiving of the Betazoid failure to offer serious resistance and they might even be considered collaborators by some.
Certain individuals would be protected against this backlash (Troi, for example, because of her connections) but the bulk of the Betazoid people would be faced with this backlash.
Sorry for the length, I came up with that for a fanfic I never wrote, because I find Star Trek pretty challenging to write.
