Tom’s Aunt Polly is his mother’s sister. She takes care of Tom and his brother Sid. She loves Tom very much, which is why she does not want to punish him when she catches him doing wrong.
He's full of the Old Scratch, but laws-a-me! he's my own dead sister's boy, poor thing, and I ain't got the heart to lash him, somehow. (ch 1)
Even though he is a troublemaker, Aunt Polly knows that Tom’s heart is in the right place. He does not feel bad about tricking people and trying to get out of work or school, but he does feel bad about giving his aunt frets. They have a good relationship, and Tom does not seem to regret having no mother. She still feels sorry for him though, and makes allowances for him because of it.