Slavery

Slavery in base game RimWorld is limited only to selling prisoners for profit, with no other use. The Ideology DLC significantly expands on the concept, allowing prisoners to be enslaved and forced to work and perform tasks.

Core

Slavery is a quick way to get decent amounts of money quickly. Pawns will suffer a mood penalty of -3 for 4 days after the slave is sold, stacking up to five times (for -15 max). Unless you have a colony of psychos, selling multiple slaves may bring down your colony by lowering the moods of pawns by large increments. There is no easy way to mitigate the negative moodlet...

One way of dealing with this is to avoid slavery altogether in the early game, and then sell only 1-2 slaves every day in the late game, when pawns can enjoy plush bedrooms and high-tech distractions, take drugs and eat lavish meals, and otherwise offset the whole unpleasantness. This has a downside, however. Slave traders only appear rarely, and then generally only stay for around two days, meaning that it will be hard making slavery a main source of profit for the colony unless you are burning through goodwill with your allies by requesting slaver caravans, or forming your own caravans to travel to villages to sell. Alternatively, you can stuff all of your pawns into cryptosleep caskets to be conveniently "asleep" during the massive mood debuff and have a psychopath trader sell as many slaves as possible.

Since there is no way to "use" a slave for anything besides trade in the base game, purchasing a slave will turn them into a regular pawn. The former slave will get a +15 mood buff for 20 days due to being freed.

Ideology

Slaves are controllable, like normal colonists, but with unique mechanics and restrictions.

Pros:

No need for recreation
Slave specific expectations meaning higher base mood
Ignore all work type incapabilities except that which slavery itself adds, therefore pawns with many incapabilities can actually be more useful as slaves.
Will never insult or social fight with non-slave pawns
Half as likely to social fight.
Significantly easier to enslave than recruit
Contribute only 75% of the value of a Colonist to Raid points

Cons:

Prison rebellions
New incapabilities: cannot hunt, make art, research or warden. Slaves are also incapable of synthesizing Drugs (cooking Drugs is still possible). Currently unclear if they can do other social activities like trade.
Suffers a x0.85 multiplier to Global Work Speed which in turn reduces: Animal Gather Speed, Butchery Speed, Construction Speed, Cooking Speed, Deep Drilling Speed, Drug Synthesis Speed, Entity Study Rate, General Labor Speed, Hacking Speed, Mechanoid Shredding Speed, Medical Operation Speed, Medical Tend Speed, Mining Speed, Plant Work Speed, Pruning Speed, Research Speed, Smelting Speed, Smoothing Speed

Expectations

Acquiring slaves

Slaves can be created by reducing the will of a prisoner to zero. This is typically much faster than reducing their resistance and recruiting them, allowing faster acquisition of pawns in exchange for the conditions and effects slavery imposes.

Slave relationships

Slaves can start relationships with any other slave or even another colonist. This is troublesome, as slaves cannot be assigned to the same bed as a colonist, but can still sleep in the same room. If you want both to be together, you need to make either both slaves or both colonists.

Slave rebellion

Slaves will occasionally rebel, staging something similar to a prison break. Slaves will turn hostile and uncontrollable, and will try to find weapons to attack nearby colonists. The rebellion interval is based on mood, suppression, proximity of weapons, and colonists present on the map, with a base interval of 45 days. The time displayed is based on time awake - that is, if a slave sleeps 8 hours of every 24, the actual mean time between rebellions will be 50% longer. A displayed MTB of 2 years will actually be a MTB of 3 years.

Slave rebellions come in several different types: Grand, Local, and Single. A grand escape involves every valid slave on the map rebelling, while a local escape choses a given slave as a locus with any valid slaves within 35 tiles also rebelling. A single rebellion is, as the name implies, a rebellion by a single slave.

Only non-downed, non-mental breaking, awake, slaves can join a rebellion. Thus, by assigning slaves different shifts, the maximum number of slaves rebelling can be limited.

Note that weapons such as Wood, EMP grenades/launchers, and Smoke launchers will not increase rebellion chance, despite being weapons. Also note that rebellious slaves will take ranged weapons, even if equipped with shield belts, dropping the belts in the process.

Mean Time Between Rebellions = 45/(Moving Factor * Suppression Factor * Slave Count Factor * Mood Factor * Room Edge Factor * Weapon Factor * Unattended Factor)

Where:

Moving Factor = A curve dependent on the current Moving capacity of the slave, defined by 3 points and linearly interpolated between them. 0.01x at 0% (though note that a pawn that cannot move is not valid for a rebellion anyway), 0.5x at 50% and 1x at 100%. This very closely approximates a straight scalar based on the Moving capacity, but is slightly different. Also note that this is Moving capacity, not move speed, so slowing a pawn down with peg legs will make rebellions less frequent, but slowing them down with a flak vest will not.
Suppression Factor = A curve dependent on the current suppression value of the slave, defined by 4 points and linearly interpolated between them. 5x at 0%, 1.5x at 33.3%, 1x at 50%, 0.25x at 100%.
Slave Count Factor = A curve dependent on the number of slaves loaded on a map, defined by 5 points and linearly interpolated between them. 1x at 1 slave, 0.75x at 2 slaves, 0.5x at 5 slaves, 0.3x at 10 slaves. 0.2x at 20 slaves. Note that despite making each slave individually less likely to rebel, having more slaves rolling for rebellions actually increases the chance. Also note that these slaves don't need to be valid slaves for a rebellion, they must simply be alive and on the map.
Mood Factor = A curve dependent on the mood of the slave, defined by three points and linearly interpolated between them. 1.5x at 0% mood, 1x at 50% mood, 0.8x at 100% mood.
Room Edge Factor = 1.7 when in a room that touches the map edge including being completely outdoors. 1 otherwise.
Weapon Factor = 4 when within 7 tile range of a usable weapon, or if indoors (in a room not considered outdoors) in the same room as a usable weapon. 1 otherwise.
Unattended Factor = 20 when on a map without a colonist that is not downed, dead or a slave. 1 otherwise.

Suppression

Suppression is one of the stats used to calculate the slave rebellion interval. The higher the suppression, the longer the expected interval in between rebellions. The suppression of a slave can be increased by interacting with them, melee attacking them with a colonist or executing other slaves or prisoners. Over time, the suppression level lowers depending on its current level by up to 20% per day.

Suppression	Suppression loss (per day)
30% - 100%	−20%
>15% - <30%	−10%
0% - 15%	−5%

This value can be increased or decreased by the following things:

Item	Suppression loss offset (per day)
Slave collar	+15%
Slave body strap	+15%
Cowboy hat	−5%
Bowler hat	−5%
Tribal headdress	−10%
Veil	−10%
Marine helmet	−10%
Duster	−5%
Marine armor	−30%
Prestige marine helmet	−10%
Prestige marine armor	−30%
Grenadier armor	−30%
Eltex shirt	−20%
Eltex vest	−20%
Eltex robe	−20%
Formal shirt	−10%
Corset	−10%
Formal vest	−10%
Prestige robe	−20%
Ladies hat	−5%
Top hat	−5%
Coronet	−20%
Crown	−30%
Stellic crown	−30%
Beret	−5%

A suppression loss of less than 0% per day will not increase the suppression. Since the default loss is at a maximum of 20% per day, a slave collar combined with body straps is enough to keep up the suppression of a slave unless they are wearing apparel that increases suppression loss above 10%. Since a negative loss has no effect, increasing Terror while slaves wear slave collars and body straps is useless unless you also wish to outfit the slave with suppression-decreasing apparel, such as dusters in hot biomes or marine armor for combat slaves.

Warden suppression

Each time a warden suppresses a slave, it increments their suppression by a value dependent on the Suppression Power of the warden and the current suppression of the slave. Namely:

*Suppression Change = Suppression Power Suppression Curve Factor**

CurrentSuppressionFactorCurve

For example, a colonist with Social skill of 10 has a Suppression Power of 28%. A slave with a current Suppression value of 0 has a suppression curve factor of 2x. Thus, that colonist suppressing that slave would result in the slave's suppression increasing by 56%. This also means that a skill 20 pawn will always fully supress a slave.

Each suppression attempt takes 180 ticks (3 secs) of work.

Authority caps improve the suppression power of the wearer. See that page for details.

Melee suppression

Any colonist can suppress a pawn by performing melee attacks against them. Each attack increases suppression at a rate dependent on the current suppression and the damage dealt, with more damage suppressing more

Terror

Terror is a way to keep slaves suppressed. It rises when the slave spends time near terrifying things like terror sculptures. A slave can only be affected by three terror sources at a time. While terror is high, suppression falls slower.

Terror can be created by having slaves in proximity to terror creating furniture like skullspikes, terror sculptures or bodies in cages. While slaves are affected by these, their suppression loss is lowered, depending on the value and amount of terror sources, but capped at 3 individual sources.

Strategies

Keep slaves in collars and straps

Consider giving slaves brain implants that cause brain shock so rebellions can be safely suppressed with no loss of life, even with armed and armored slaves, by using EMP weapons.

Wimps also make for easily quelled rebellions.

Titles

Main article: Titles

Slaves can be given honor and ascend the ranks of royalty just as every other pawn can. They function much the same as other nobles, requiring specific clothes, certain standards of bedroom and throne room, etc. with two major exceptions. First is they cannot use permits. Second is that slavery overrides the work type restrictions from conceited nobility

Version history

? - Slave sold penalty reduced from -5 to -3, sometime between 1.2.2723 and 1.3.3087
1.3.3072 - Tune slave rebellion chances a bit lower, and reduce the effects of some factors. Slave weapon noticing distance reduced from 10 to 6.9. Couples made of a slave/colonist pair no longer want to sleep together despite not being able to share a bed.
1.3.3074 - Slaves no longer slight or insult non-slaves, Slaves never start social fights with non-slaves if insulted, Meleeing a slave now increases suppression, Rebellion chance per slave now relates inversely to the number of slaves on the map, so overall rebellion chance shouldn't climb so aggressively with higher slave counts, Adjust slave rebellion base MTB 50 days back to 45 days. Ideoligion funerals are no longer expected for slaves. Slaves no longer count for Diversity of Thought. More selective in which weapons increase rebellion chance - now excludes Wood, EMP, Smoke etc.
1.3.3076 - Added Alert for likely slave rebellion.
1.3.3080 - Rebelling slaves now drop shield belt if they have a ranged weapon
1.3.3087 - Lower slave social fight chance by 50%. Killing a slave in a slave rebellion no longer causes 'Witnessed ally's death' thought
1.3.3200 - Slaves are now worth 75% of colonists in terms of map wealth and population.

Expectation	Mood Effect	Wealth Range
Destitute slave expectations	+46	?
Poor slave expectations	+40	?
Meager slave expectations	+34	?
Slave expectations	+28	?