William Twotrees is the illegitimate son of 1940s hero Johnny Thunder and a Jicarilla Apache woman. Afraid of prejudices against mixed marriages, Johnny abandoned his son, something he later regretted deeply. However, it seems as if Johnny's partner, the magic Thunderbolt named Yz, left his mark on young William, who developed astonishing thunderbolt powers later in his life. As Willpower, William joined the supernatural/meta-human team of heroes called the Leymen (a.k.a. Primal Force) until it was disbanded. He was last seen searching for his father, touring with a rock band as a "human light show".
Given that Twotrees has neither reappeared since the cancellation of the Primal Force series nor been referenced in any way in the later Justice Society of America titles, it is unknown whether this story continuity still exists in the aftermath of the Infinite Crisis and Final Crisis storylines.
The DC Comics Encyclopedia