Why does Frannie sit down near Maribel and what does she think about Maribel?

Frannie sits across the table from Maribel because that's where Samantha is sitting. Samantha is Frannie's best friend and she wants to sit with Samantha, even if it means that she has to sit across from Maribel. Frannie doesn't like Maribel and thinks Maribel tries to make herself seem above everyone else.