Slavery isn't really something that I put much thought into while writing for my worlds, but, thinking about it, it should be a part of it, in some shape or form, while writing for different planets and cultures, the best way to make them feel like different locations and people, it's good to cover topics such as this.
Kah-Vita
While they don't enslave people, the Kah-Vitans are a warrior race. They have multiple clans, who in the current day, (It being a futuristic science fiction setting) have remained true to themselves and their traditions held for so long and passed down to them from their ancestors.
Each of these clans is powerful, and usually infighting is common among them. However, when the Confederation invaded, many of the clans joined together in order to defend against the outsiders, and they were incredibly successful in their attacks.
One huge story amongst the clans is how one of them, who wasn't even the largest of the clans, managed to take down a capital ship - the flagship of The Confederation. This ship was stuck in the sands, with no hope of evacuation. The entire Confederation called a retreat, but, the survivors of the crash were stranded out of contact with the rest of their forces.
All of the clans of Kah-Vita were put to shame, disgraced that they were not the ones to take down such a prize, so, in order to prove themselves and reclaim their honor, they had no choice but to mount attacks against the invaders, hoping to be the ones to kick them off Kah-Vita once and for all.
With each passing day, the survivors dug in and defended against each onslaught, as the days dragged on, these attacks became less of a problem for the defenders.
Kah-Vitan Tradition
For the clans, it was a tradition passed down to them to take trophies, in the form of men and women captured on the battlefield. Each clan would decide for themselves how long a particular trophy was kept around, and that usually depended on the level of the person.
If it was a high-ranking member of another clan, they would be treated the best, paraded around, and used as a way of showing all of the other clans how well they treat their prizes. They would be fattened up, bathed, and looked after in every single way, the more the clan looked after them, the better the clan looked to the others.
Another reason for this was that a clan leader was able to show how they do not hold grudges.
One story tells of a clan leader known as Cinnri Madi, who was the leader of a particularly small clan known as The Dridi Raiders. They were from a small spit of land known as Dridi and were constantly harassed by a much larger clan known as The Barki Wanderers; who were nomadic to a certain extent, but only stayed in one particular region, the Toke lands, by the large river separating this region of Kah-Vita from the other.
The Barki Wanderers weren't like other clans, as found out soon by the clans of this region. They organised a brawl with the Dridi Raiders, to which all of the warriors raced for a chance to stop the Barki raids, once and for all. Some other small clans even got involved.
They waited, and waited, and there was no sign of The Barki Wanderers, upon returning home, they found out why. While the clan's warriors were waiting in a field, The Barki Wanderers diverted course and attacked the undefended villages.
Skirmishes took place here and there, but nothing major, then, there was a meeting between all the clans in the area to attack and kill every one of the Barki Wanderers for dishonoring themselves.
After the battle was done, Cinnri Madi held the leader of The Barki Wanderers and took him to every clan far and wide, it is said over the weeks and months the leader of the clan grew so fat that they couldn't walk unaided. Cinnri himself helped in carrying the burden of the man.
For low-ranking members and foot soldiers, a few days and nights were enough to show them off. The Confederation learned this upon crash landing, when the prisoners were returned, they were thoroughly inspected, as The Confederation was afraid that there was an ulterior motive to bringing the captured soldiers back.
The Hands of Tahl
These were the last of the clans to strike, with them, they brought an army, the numbers of which swelled and were ready to burst onto the wasteland outside of the walls of the settlement.
Many clans had entirely been vanquished, but, the survivors of those clans flocked to the banner of The Hands of Tahl, in order to earn a good death in battle.
They did, and the survivors, maimed in the fighting slunk back into their towns and cities, disgraced multiple times on the battlefield. These people returning home clan-less swelled the numbers of Fog Dealers, and over this time many Fog Dens were erected, giving the clan-less a place to go and forget about the dishonor they received.