Also known as Logic or the Unchanging Queen, Sorcha is the Queen of the High Court. She is intrinsically linked to the other world of Faerie and as a result she cannot leave it; anywhere in the mortal world that she attempts to go is consumed by Faerie. Frequently, Marr describes Sorcha and Bananach as the engine that drives magic- they oppose, but one cannot exist without the other. To destroy either- though it does not seem possible- would create a domino effect that would eradicate all faeries everywhere.
Sorcha first appears in Fragile Eternity, and she is described as being physically very beautiful (like all fey)- tall with flaming red hair, preternaturally long slim fingers and an air of being temperate. Her skin is threaded with fine silver lines and when she sits on her throne in the Hall of Truth and Memory the silver in her feet connect to the silver in the earth. She prefers to dress formally. Her nature opposes that of her sister, Bananach, and her appearance is intended to reflect this antithesis.
Sorcha is almost omnipotent in Faeire when her character first appears. As an extremely powerful monarch, she remains unaffected by steel. Only her twin sister and opposite Bananach can harm her, and her Court is powerful enough to overrule the Dark Court if it were to return to Faerie. As a result, she maintains ultimate control throughout Faerie. She can manipulate the landscape, weather and day-night rhythm, and can change objects from one form to another. For example, in Fragile Eternity, she transforms Seth's mobile phone into a swarm of butterflies and back.