His features are described as unusual for a witcher, as he retained scars from early childhood diseases, like chicken pox, which he covers with a beard, while most witchers were immunized before contracting such illnesses. This would suggest that he either contracted the disease unusually early in life, or that his witcher training began later than most.
In 1265, Coën spent his first winter at the Wolf School's fortress Kaer Morhen when Ciri was in the keep. He trained her in the ways of sword combat with Geralt, Lambert and Eskel. One day during her training, Ciri entered a trance and foresaw the deaths of both Geralt and Coën. After a while, Geralt called for the sorceress Triss Merigold, who introduced herself to Coën. Throughout his time at the keep, while not training and playing with Ciri, he helped look after the stables and horses.
In 1268, Coën participated in the Second Northern War, and died in the Battle of Brenna (as Ciri foresaw). He was stabbed with a pitchfork or a two-pronged guisarme through the heart in battle and had his aorta split open, but continued to live until the squadron brought him to Milo Vanderbeck, a halfling and a field surgeon who was better known by his nickname, "Rusty."
- In The Witcher, the gardener at St. Lebioda's Hospital relates a story about a silver sword belonging to Coën. Shani also fills in some details about him when Geralt asks her about the sword.