Who is Uncle Squinton Leach from The Mostly True Adventures of Homer P. Figg and what is their importance?

Uncle Squinton Leach is the uncle who takes custody of Homer and Harold after their mother's death. Squinton was married to the sister of Homer's mother, but she was long dead before Homer's mother died. Uncle Squinton is a cruel man who kept the children just to force them to work. Uncle Squinton sold Harold into the army, the act that began the conflict that will propel the plot of this novel.