Dolls are a “race” (term used loosely) of living constructs, made in the image of some other race (usually Humans.) Being artificial, they lack a soul and all of the benefits of having one.

They're highly discriminated against on Terra, and creating them is illegal in most jurisdictions.

Dolls are made in the image of some other race, so their physical description matches the race they're crafted after perfectly. There are no physical differences. However, due to their lack of soul, their eyes are “empty.” A complete lack of light or life in their eyes.

Additionally, they have a tendency to “idle” when they have no assigned tasks or survival necessity at the moment. They will sit (or sometimes stand) perfectly still, sometimes for hours on end, staring into space. When in this state, they appear to simply not notice the happenings around them. This behavior is where they got the name “Doll” from, as they appear as lifelike mannequins.

They typically speak very little, and usually perform whatever tasks are given to them. They don't feel emotions the same way ordinary people do, but do appear to feel them to some degree. Their expressions are usually very blank, with only slight adjustments visible.

A Doll's empty gaze has the supernatural ability to make those who peer into it uncomfortable, at the very least. Many will begin to feel dizzy, or even that they may pass out. Many are superstitious that Dolls can steal one's soul by making eye contact, but the actual mechanism for this symptom is unknown.

Dolls do not appear to often be aware of this “feature.” They often have to be reminded to not make eye contact with others.

Dolls are infamous for their tendency to go berserk. If they have nothing to ground themselves with, and if they're left to be feeling like an outsider for too long, they inevitably begin to wonder what sets them apart from the rest. They hear others call them 'empty,' or maybe learn that they lack a soul. They begin to feel a desperate need to remedy this.

Once a Doll begins to berserk, they will hunt down and kill others, in hopes of finding what they lack. No matter how many times it doesn't work, they'll try again and again, growing more frenzied as time passes.

It's possible to prevent a Doll from berserking in the first place by simply giving them a feeling of belonging. They will often 'anchor' themselves to a favorite person who treats them well, and so long as they have access to this person, it's generally enough.

It's also possible (though far more difficult) to reverse the berserking process by similar means.