Source: The Witch Queen's Revenge, pg(s). 88
Poludnicas are bitter, lonely fey tethered to the Material Plane by their connection to the sun. They yearn for a family life that they could never get, and lure mortals away from their families, expecting to be loved and considered as family by them. Rural dwellers sometimes refer to a poludnica as Cornwife, Lady Midday, or Mother Noon.
Poludnicas draw sustenance from sunlight. Their maximum life expectancy is unknown; it is theorised that they are effectively immortal unless killed. According to a hypothesis (which no scholar has tried to prove), keeping a poludnica in darkness for a sufficient amount of time would kill her. They also need companionship and the replication of a family life, and are willing to go to great lengths (up to and including murder) for emotional sustenance.
At night, a poludnica is magically pulled into the Ethereal Plane, where she is distressed, helpless, and can do nothing other than move on the Ethereal Plane or gaze into the Material Plane. They use this ability to watch mortals eat, sleep, and enjoy companionship, filling themselves with sorrow (and sometimes rage), and driving themselves slightly insane.
Each poludnica claims a few hundred acres as her territory, and makes her lair in an inaccessible, hidden, or shunned place, where she builds a mockery of a human house. By day, she seeks to bring a farmer or child there (whether willingly or not) and expects him to provide her with companionship or intimacy. Those that try to escape before dusk rarely survive. At night, the poludnica fades away, leaving the abducted person free to flee, but this is often difficult due to the inaccessibility of her lair. If he is still there by dawn, the poludnica simply returns, unhappy by how her new 'family' member is disloyal to her. The rare kindest poludnicas avoid all contact with farmers and only watch them at night to enjoy a companionship that they themselves can never have.
Due to their crop-enriching powers, many communities view them as guardians. Children often make dolls from cornhusk to appease a local poludnica, ask for her protection, or thank her for sparing their family; sometimes, such acts can actually cause a touched poludnica to stop or reduce her abductions.
- Lady Midday (real-world mythological creature) on Wikipedia