Sister Apple

Sister Apple is a Grey Sister (Sister of Discretion) of Sweet Mercy. She's also Mistress Shade, teacher of Shade Class at the convent, although the novices called her "The Poisoner" behind her back, because she focuses almost exclusively on poisons and antidotes in Red Class. She and Sister Kettle are lovers.

Appearance and Personality
Sister Apple is young, green-eyed, with red hair and tall with curves. She often has a warm smile on her face, but hidden behind that is a biting wit and sardonic sense of humour. She teaches the novices to be vigilant by constantly trying to poison them; no new novice escapes being poisoned in their first class.

History
When Apple joined Sweet Mercy as Mistres Shade, Kettle was in Holly Clas. The pair became close, which caused tension with Kettle's former lover Safira. During a jealous rage, Safira stabbed Kettle in the leg and was expelled from the convent

Red Sister
Sister Apple and Sister Tallow go with Abbess Glass to bring Nona Grey to Sweet Mercy. It’s clear that they are wary of the Abbess’ decision to enter the convicted murderer as a novice in the convent, but the Abbess tells them, "You’re nuns. Show a little faith." Apple takes Nona to the Nuns' Dormitories on her first night and to the bathhouse the next morning.

Sister Apple successfully poisons both new novices, Nona and Arabella, in their first Shade Class, although it takes three attempts with Nona. Later in Grey Class, Apple poisons Nona again, this time with Clera. Clera is unwise enough to complain about only observing in their first Shadow-Weaving lesson, so Apple poisons the pair with her latest truth serum. During the Ranging, Sister Apple and Sister Kettle are secretly tasked with following Arabella and Nona, and keeping them safe. Kettle encounters a Noi-Guin assassin trying to kill Nona, and gets stabbed with a poisoned knife. Nona finds her, and forces her to call Apple for help via their Shadow-Bond.

Grey Sister
Two years ago on the Ranging, Sister Apple rushes to help Sister Kettle. In her hast, she gets caught by a group of Durnish raiders. She poisons them all by pretending to be just a helpless nun, but leaves them the antidote saying, "It’s all very embarrassing. I won’t tell if you don’t." She eventually arrives to find her lover barely clinging to life. Together they diagnose the poison on the blade as Dark-Venom, a poison with only one cure, to be pushed into Shadow. The cure is forbidden by the Ancestor Church, but she reluctant agrees with the words, “Poisoner, poison me”.

In Grey Class, Sister Apple focuses on preparing the novices for the Shade Trial with lessons in disguise, discretion, and trickery. The taciturn Zole proves a particularly inept student, totally unconvincing as a merchant’s daughter who loves to dance. Nona isn't convincing either, but finds her own way to succeed at the trial.