Why dose squeaky dislike Mary Louise?
Squeaky describes Mary Louise as ungrateful. Introducing Mary as her “used to be friend", Squeaky says "when she (Mary) first moved to Harlem from Baltimore,” everybody would bully her and beat her. But as because both of their mothers used to sing in the same choir, Squeaky decides to help her. She becomes her friend and doesn't allow anybody to cause her any trouble.
But they are no more on friendly terms. Mary’s found new friends in Gretchen and Rosie. Gretchen is a good runner and the only contender for Squeaky in the May Day race. Squeaky says,
“… now she hangs out with the new girl Gretchen and talks about me like a dog;”
This implies that Mary speaks ill of Squeaky and scorns her before Gretchen and others. Before the May Day race, she attempts to annoy Squeak by saying to her,
“You signing up for the May Day races?” smiles Mary Louise, only it’s not a smile at all.
Mary knows it very well that Squeaky is the fastest runner and she has never lost any race. There's no doubt about Squeaky's participation in the race. She makes this irrelevant question solely to provoke her.
Later, with an intention to trouble Raymond, she asks him, “What grade you in now, Raymond?”
Squeaky is aware of her intentions. She retorts saying,
“You got anything to say to my brother, you say it to me, Mary Louise Williams of Raggedy Town, Baltimore.”
Thus, Mary's ingratitude, her uncalled-for provocative remarks and her treatment of Raymond are enough reasons for Squeaky to dislike her.