The Subjects

I’ve watched them carve subjects – carve people  up from the inside out, like we’re all hulls waiting to be shucked.

The subjects of Aurora Silver are various people who have gone through the cult inflicting The King on normal civilians. She presumably uses them to attempt to find the King.

Subject 7825
7825 was Mabel Martin's designation during her time at El Segundo Academy. While little is known about the experiments she went through, it is clear that they were painful. At one point, they run an experiment only for Mabel's voicemail to echo over and over, steadily distorting.

Subject 6163
6163 was Ekaterina Roskova's designation during her time at Saint Olga's Preparatory. She was tortured until she forgot her name, and eventually summoned some form of god after reciting a prophecy. After she summoned the god, she died and went into the Underhill, becoming Aconite and experiencing total amnesia of her life before until the girls played her one of the tapes of her torture. She regained her memories and Mabel told her Aurora Silver would be looking for her, and that she should not leave the House for fear of death.

Tressa Davies
While she has no designation, Tressa Davies was often summoned by Aurora Silver to complete small tasks (such as describing her emotions when holding certain things), counting her as a subject during her time at Lang Primary Conservatory for the Disabled.

Subject 4583
4583 has no known true name. His test held him screaming and, eventually, his screams turned to stag calls before wet splatting which sounds like a body exploding played. It can be assumed he is dead.

Subject 5712
4583 has no known true name. Their test involves them hollowly repeating the words "It's really you. I missed you so much." over and over. Their fate is unknown.

Subject 1138
1138 has no known true name. Their test involved them apparently shape-shifting (making infant wailing noises into loud, adult laughter and distorted screams) before they say "Fiat justitia et ruat caelum" ("Let justice be done though the heavens fall", meaning that justice must be served "regardless of consequences"). Their fate is unknown.