Tremble with awe and fear. Here comes the enigmatic Subject 27.
No one of the Kate's retinue knows nothing about 'it'. It - because they have no idea what gender this person possesses. It always wears a long coat and a gas mask. (literally always) No one ever saw it without clothes (except of Kate). This person doesn't eat, and doesn't need any water or other liquids to sustain itself.
Rumor is that this person was so injured during the combat, that all it's body is a big scar, and it doesn't eat because 90% of it's body is artificial. Other rumor states that Subject 27 is a disguised daemon host. There are plenty of such guesses around this person, but no one knows for sure, except Kate. But Blackwing has no desire to talk about 27's past.
Another rumor states that Kate almost got herself killed by the fellow inquisitors trying to save 27. That conflict still haunts her in the form of assassins, false accusations and other inquisitorial 'payback' methods.
Subject 27 is a tremendously powerful psyker. Mind reading, telekinesis, pyrokinesis, warp lightnings and other 'psy tricks' are at it's disposal. During one combat it killed a chaos dreadnought by squishing it to the size of a suitcase.
Other members of Kate's retinue often see Subject 27 injecting itself with some strange glowing blue liquid, but Kate gives no comments about that.
27 has a slender build, and is very weak in terms of raw physical strength. One day Mary offered 27 a friendly arm wrestling match, and Mary won despite of the fact that she's just a small-framed girl.
Subject 27 is calm and caring. But it has not many chances to demonstrate it's good nature to others - people tend to stay away from 27, which offends it greatly.
27 communicates with others with the help of vox-transmitter, integrated in it's gas mask. It talks with a low distorted mechanical voice. Mahina very likes this voice and calls it 'sexy' when 27 doesn't hear her (as she thinks). Strangely, 27 doesn't like to communicate with people telepathically. The theory is that it doesn't want to scare people away by 'talking in their heads'.
Subject 27 is kind-hearted and very shy. It's hard for it to come to someone and start talking. Usually 27 leaves a note on the place where the person it wants to talk surely will notice it.
The majority of Kate's retinue loves 27. Except of A-LIC-e. She has a grudge against Subject 27, because one night it saw A-LIC-e's nightmare and occasionally red her thoughts - by that 27 received the information about her tragic past.
Subject 27 is very loyal and helpful. Kate likes 27, and often takes it with her as a personal bodyguard/lie detector/interpreter.