Kestka appears as a withered, ancient crone standing just over seven feet tall, her narrow body bent forward as if perpetually listening to the floorboards. Her flesh is dry and gray-brown, textured like old birch bark stretched over wire. A pair of jet-black raven wings folds from her shoulders, each feather glossy at the edges and ragged near the roots, as though plucked and regrown a thousand times. Her fingers end in long, flesh-shearing talons that click together when she thinks. A small donkey's tail protrudes through her layered robes and swishes with startling impatience. Her jaw is too broad for her face, and when she laughs, her gums pull back to expose square, humanlike teeth packed in several uneven rows. She grooms those teeth obsessively with a silver pin, yet leaves her hair in a tangled white rope that trails almost to her knees. She moves with contradictory grace: her wings twitch like a nervous bird, while her feet place themselves with the silent precision of a dancer.

Kestka is observant, exacting, and unexpectedly patient. She can be generous toward strangers who have nowhere else to turn, yet becomes jealous and controlling toward those who depend on her. She delights in exposing hypocrisy but hates public humiliation when it is used against the powerless. In a calm mood she is almost grandmotherly, correcting posture, mending clothing, and offering bitter tea. When insulted she becomes ceremonially polite, each word clipped and carefully sharpened. In private she is sentimental about small acts of care, though she would rather claw through a door than admit it.

Kestka was once a mortal midwife in a wind-scoured settlement where hags were blamed for every stillbirth, failed harvest, and missing child. She learned early that frightened people preferred a monster with a name to a tragedy without one. During a famine, the village elders demanded that she sacrifice an infant to appease a local hag. Kestka refused, hid the child beneath her floor, and accepted the blame when the crops failed. The villagers burned her home around her. As she died, the child crawled from the cellar and placed a black feather in her hand. That feather belonged to no natural bird. It carried the attention of Mestama, who offered Kestka a choice: die innocent, or live forever as the shape mortals feared. Kestka chose the latter and became the goddess's first living vessel, later ascending beyond the need for a vessel at all. The experience changed her permanently. She stopped believing that innocence protected anyone, but she never stopped protecting abandoned children. In the present age, she rules a hidden court of hags beneath a ruined hospice, where she gathers secrets, settles grudges, and quietly undermines gods who promise comfort without demanding a price.