Slave Traders are NPCs. They will not attack the player. But if a player controlled unit get unconscious close to them, they can heal them and take them to Slave Traders Camp in the north-west(Needs Verifiation), where the unit will be forced to work.
If the unit is unconscious, it will be taken first to a cage while healing. Then a slaver will come to the unit and take them to work.
Slave Traders will then watch the unit move and work, and will taunt it and remind him his duty.
At night, the slave will be taken back to a cage, where he can try to unlock or destroy his shackles.
From time to time, some slavers will come to the camp and buy or rent slaves, including the player's unit, which will now follow the caravan for a while, then sometimes returning to cage.
Slave Traders caravans can also bring new slaves, like bandits, and warn everyone that non-workers will be brought to furnace.
If the player tries to runaway, he won't be able to run at full speed because of shackles, will be called a runner and will be attacked by everyone.
|“||The slavers will enslave people that are unwilling to pay fees or were foolish enough to fight them.||”|
–Note for a future update from the website of "Kenshi"
If the character talks to the slavemonger in a slave trader group, it is possible to buy slaves from them, but it is currently unknown how to get the slave to do anything.