Keot

Keot is a Demon, a mysterious entity bred by The Missing. He originally possessed Raymel Tacsis and then crossed into Nona Grey when she killed him.

Appearance and Personality
Keot is a Demon who either resides at the boundary of death or possesses a person. He can move around inside the person he has possessed and be glimpsed on their skin, but generally keeps well hidden from others. Nona describes him as "a broken thing, part of a mind perhaps, filled with fragments of knowledge, occasionally useful." He seems to become more coherent when in proximity to a Shipheart. Keot loves nothing but violence. When the person succumbs to his urging, his bond with them is strengthened, but when they show mercy or compassion he is weakened.

Red Sister
When Raymel Tacsis is mortally wounded by Nona, he is kept alive by a group of Academy mages who hold him at the boundary of death, until his body heals itself. It is a dangerous process, that risks the patient becoming possessed by the Demons that dwell at the boundary. Keot is one of the four Demons who possess Raymel. When Nona kills him during the Ranging, Keot crosses into her. The Demon claims that the pleasure Nona took in killing her enemy had let him get under her skin.

Grey Sister
Keot has possessed Nona for two years. He speaks to her and urges her to violence, which she struggles to resist. Upon joining Mystic Class, Nona immediately gets into a feud with another novice, Joeli Namsis. Keot tried to convince her to kill Joeli, and Nona almost loses control one day in the Blade-Hall, pinning Joeli to the ground, until her friends to drag her away. When Nona explores the undercaves searching for a route to the spot where her friend Hessa died, they encounter a Holothour, another mysterious entity bred by The Missing. The Holothour causes the novices to flee in panic, to dread returning, and even to forget the experience; only Nona is not effected thanks to Keot. During the Shade-Trial, Keot helps Nona to avoid getting caught, by stopping her sneezing. In return, Nona promises to kill Yisht.

When the Inquisition have descended on Sweet Mercy and Nona is forced to flee the convent, Keot continues to help her. At her mother's village, Giljohn the Child-Taker tries to shoot her with a poisoned crossbow bolt, but Keot warns her in time. He also encourages her to escape from the prison cell in the Tetragode, fearing he'll be forced to return to the boundary if she died. He does nevertheless consider crossing into Thuran Tacsis when she died, admiring his cruelty. During her escape, Nona kills many Noi-Guin and Lightless. She notices that when she kills, Keot’s bond with her seems to strengthen, and when she shows mercy or compassion it weakens. In Sherzal's palace, Nona and Sister Kettle get into a fight with Yisht. Yisht tries to force Nona to flee by threatening the injured Kettle, first cutting her throat and then holding Grey Mustard poison over the prone nun. But Nona is determined not to leave her friend. This act of compassion forces Keot to leap from her into Yisht, who is already possessed by numerous Demons from her contact with the Sweet Mercy Shipheart. The introduction of yet another Demon inside Yisht, causes her to stagger away writhing, and allows Nona and Kettle to escape. Afterwards, Nona finds she misses the Demon's advice, even if she would probably opt to do the opposite.