Flaygian Screwte is a member of the Myreque. He can be found in the Myreque hideout in Meiyerditch (not to be confused with the base in Burgh de Rott). He is the scientist and researcher, working directly under Safalaan.
Prior to Legacy of Seergaze, Flaygian has made a rough translation of the Haemalchemy book that the player found during The Darkness of Hallowvale. Throughout the quest proper, he sends the player on a variety of "missions" to help design a weapon capable of harming the vyrewatch; these include researching the most adequate weapon type, finding and repairing a furnace in Meiyerditch, and gathering the components for building an Ivandis flail. He eventually leaves the base due to becoming extremely frustrated for not being able to successfully construct the flail, as he is a theorist and has poor practical skills. Although he supposedly wanted to take a stroll and have some fresh air, he doesn't return to the base afterwards.
In The Lord of Vampyrium, Vertida Sefalatis will only say that it's more comforting to think of him as dead rather than a coward when asked about his disappearance. Before his disappearance, Flaygian designed a new crossbow for Vertida, capable of firing blisterwood stakes. Vertida nicknamed it "Screwte" in honour of Flaygian.
During River of Blood, his severed head is seen on a bookshelf where he questions why the player is not using his superior flail design and the youngster is instead using blisterwood.