Welma Thornwood was the woodtroll nanny of Maris Pallitax. She took care of Maris's pet lemkin, Digit. Welma appeared several times throughout the events of The Curse of the Gloamglozer. During the events of The Winter Knights, Heft Vespius fraudulently gained control of the estate of Linius Pallitax and fired Welma, and she took up work in Undertown with Tweezel, seizing every opportunity she could to check on Maris in secret.
Welma was generally a kind and caring individual. She loved Maris deeply and often acted as a mother figure to her, frequently comforting her when she felt neglected by her father. She taught Maris much of the knowledge and wisdom of the Deepwoods people by telling her stories like The Tree That Said It Could Fly, cooking traditional foods like Wodgiss Spiced Scones and teaching her about treatments for wounds.