- "I would think about him when I was working, when I was drinking, when I was having a shit. It got to the point where I would say his name every night before I went to bed: 'Willem, Willem, Willem.' A prayer almost."
- ―Yoren about Willem.
Willem, for unstated reasons, killed Yoren's older brother and fled town that night. From then on, Yoren became obsessed with him, thinking about him whenever he did anything, going as far as to whisper his name every night before going to bed. Willem returned to his hometown years later and Yoren says he "buried an axe so deep into Willem's skull they had to bury him with it". Willem's horse took Yoren to the Wall.
In the books
In the A Song of Ice and Fire novels there are several characters whose first name is Willem (Willem Darry, Willem Frey, Willem Lannister), but none of them has anything to do with Yoren or his family. Yoren never speaks of his relatives.