King of the Niskies, Fossegrim is the Brook Horse, a legendary equine-featured nisky lord who is second only to Green Arbor in the Viridian Courts of Faerie. He is her closest political ally and one of the most ancient faeries on Shem. He is also a friend to the Roma and the Riverkin, and he is known to many as a dangerous enemy for his ability to draw in mortals and drown them.