Monk
The Grunts, of all of the races in the Covenant, resent and dislike it the most.
So much so that in order to stop the last rounds of the Grunt rebellions, they had to glass their homeworld. An act that only brought temporary peace because it turns out that destroying a species' homeworld is one of those things people remember and deeply resent. The Grunts have been on the bottom of the Covenant's totem poll since they were conquered, something they have also deeply resented.
New species brought into the empire often come in at a higher caste than them, they're not allowed to hold any positions of government. Even on Grunt-held worlds, pretty much every government post of any kind of authority is almost always denied to them. There are exceptions of course, from time to time a few rise up to some position of power, but it's rare and those that rise up are never given the respect that the position should afford them.
It's the perfect breeding ground for another rebellion and, looking at the numbers, another Grunt rebellion right now would break the empire. There is however a problem: the vast majority of the Grunt population has been cowed by the threat of being glassed, of the genocide of their entire species. Their industry is also kept purposefully more primitive than everyone else's while their ability to travel and to build ships is also limited.
You can get riots but they won't go to civil war, not alone.
An anti-war movement? A growing one, at that. Oh, that's an easy sell. Package it with some music, and an ability to dodge the police, and you are good.
Going to be honest: the first Radioman was not my doing, that was spontaneous but I was able to secretly send him music and tech once he started. The ones that came after him? I made sure they found the tech, made sure they had the music. You would think the Covenant, as a religious theocracy, would understand the idea of a martyr but they really don't. Each Radioman killed just leads to more people taking on the title.
It's not my revolution anymore, it's not my movement. I may have given them the tech and the seed money but they took it and ran with it. It only took a little bit longer for the Grunts to create their own rock bands.
"They're calling them rocker boys."
Theocracies are not known for their musical prowess, their artistic prowess. Musicians, artists, the entire creative community has been captured by the Covenant's church for so long that the idea of music outside that world is pretty much unheard of for the most part. Create a musical scene outside of that? Music for the people, by the people?
Yeah, it's catching on.
"We're making progress."
The Grunts were a good start but then I looked at the Elites. The right-hand men of the Covenant, the people who truly made it what it is. The Prophets never liked sharing power with them and had been on the lookout for a more pliable replacement for a while. It was stupid, the Elites were damned good at their job and they had served loyally for just as long. But they were a practical people and could and would tell the Prophets no when their utopian bullshit went too far.
A thousand years ago the Elites were celebrated for that, for being the secular sounding board that kept the empire intact. A hundred years ago the Prophets at least tolerated dissent, in light of what the Elites brought to the table. The current leadership? Spoiled little shits who lack the moral fiber of their forebearers. They hate being told no, even when it's in their own interest.
They used Black Harvest to completely jettison the Elites from their traditional roles in the power structures. Brutes became the generals, the admirals. Basically, every role of traditional importance went to the Brutes and they were losing badly. The only place where the Elites retained their traditional powers in the military was special forces. On the other hand, The Elites still held the vast majority of the empire's shipyards, the majority of its industry, and their resentment was growing.
But it wasn't at a boil yet, wasn't ready to explode. We needed to hold out longer but I already saw the cracks in their empire and, when the time came, I would rip it apart.