Only known is his father, Gilneas Army Officer. Blackwood senior wanted his son to join the Army, however, young William never wanted to have anything to do with military discipline and wished to be a common man, becoming an expert hunter, woodsman and skilled fisherman.
His father died in an accident during some military training manoeuvres. William inherited a house, and very little portion of land (it was not mentioned, though, where exactly), but he sold everything except the house, where he lives now with his pack of dogs.
Until the curse of the Worgen, he lived away from society. Due to him being an outsider he avoided infliction.
After the Forsaken invasion he left his house and headed South, with only one dog who managed to survive. He spent most of the time hiding in Blackwald.
He eventually headed back to Gilneas, hoping to serve Duniths, a small noble family whose territories began right at the edge of his home.