Who is Lezek from Mort and what is their importance?

Lezek is Mort's father. He specializes in distilling wine from "reannual" plants. Lezek takes his son to Sheepridge on Hogswatch Eve in order to find a master willing to take him on as an apprentice. Lezek believes that Death, who he cannot see or hear clearly, intends to train Mort as a mortician.