Vesemir was the oldest and most experienced witcher at Kaer Morhen in the 13th century and acted as a father figure to Geralt and the other witchers. Like many of the other witchers, he spent each winter in the fortress and set out on the path when spring arrived. He was one of the few members of the School of the Wolf to survive the assault on Kaer Morhen. By 1260s, he was the sole old witcher remaining; however, as he was only a fencing instructor, he didn't possess the knowledge necessary to create new mutagens in order to mutate more disciples into witchers.