Since we have the option for three personality options here I didn't want to waste them.
A. Perhaps her new roomie is a nice girl in her Senior year at Buttercombe. You know the kind. Little miss perfect, they seem to get straight A's on all their tests, but always complain they aren't studying enough. Goody two shoes. Yeah Beth hates them too. Maybe she even getting into a mental competition to at least out-eat or outweigh the already heavier girl who in turn seems to even pack on the pounds ever so easily.
B. Big and bossy the new roomie is basically a taste of Beth's own medicine. How bad could things get? Perhaps a turf war as the two split the room in half. Perhaps the new roomie is so much a bully that egotistical Beth's is forced to be her lackey/servant. Who can guess.
C. The bigger girl is up to the very next poster to decide. Who know what they can think of!