Have it all generated in world gen, prehaps you will be part of a dwarfen civ that doesnt care about slavery and you can slave or unslave.
Prehaps your part of a dwarven civ that does care about slavery and your not allowed to enslave.
Prehaps your part of a dwarven cig that FORCES you to enslave the defeated enemys.
Bad thoughts would be generated if you did not follow these.
"Saw an unslaved -- prisoner"
"saw a slaved --"
And the ones who dont care dont care.
I believe that if we do include slaves that another noble be included, slave driver or w/e, have it a seperate noble.
Having the slave driver would allow for the enslaving of prisoners, not unlike the taming of animals from the dungeon master. In such i mean the slave driver/master w/e drags the slave from the cage to their workshop or w/e and then enslaves the,.
Slaves would work for the fortress and not under specific dwarves.
They would basically be haulers, hauling things from place to place as they would not be trusted to manufacture things of certain things (metal for example... stone may be usefull for slave workshops

)
And to the guy below me slave managing as a labour would be intresting and if we have it like that then theres no need for a noble. But have slaves work under the fortress and not under one dwarf.
Slaves would try to escape...
Slave -- cancles hauling object: trying to escape.
at that point the slave would become hostile and try to escape.
Its going to be hard to fully impliment slaves if slaves are implimented.