William is the husband of Elizabeth Keller and father of Hellion and James Keller. He and Elizabeth made a deal with the Kingmaker to become extremely wealthy. 
 
After Hellion and the Hellions battle with the Kingmaker in Los Angeles William and Elizabeth disown Julian, much to Julian's chagrin. The abandonment is complete when Julian goes looking for his parents after nearly being killed by Lady Deathstrike, William and Elizbeth moved from their home and didn't tell Julian where they were going.