What is the significance of Elsa's Gryffindor scarf in the novel, My Grandmother Asked Me to Tell You She’s Sorry?

Over the course of the novel, Elsa's scarf becomes a symbol of the bullying she endures at school. Elsa is a big fan of the Harry Potter books, and early in the book, her scarf is damaged, apparently in a fight. Later, Elsa is offended when a girl makes fun of the scarf. For Elsa, the girl's lack of understanding and tolerance about the scarf is just another in a long line of episodes of teasing and bullying.