Elsie was more stand-off than actively disagreeable and kept herself to her own cubicle, but Mabel was openly annoying.

She transgressed every rule of dormitory etiquette, dashed for the bathroom instead of waiting her due turn, dumped her belongings on to other people's chairs, spread the center table with her papers, fidgeted during study hours, and in various ways made herself objectionable.
Irene and Lorna, as sworn buddies, cemented yet more firmly the bond between them, and supported one another on every possible occasion.
Irene was really growing fond of Lorna.

Though the latter might be reserved it was something to find a ready listener and sympathizer.

As a rule we can't deliberately choose our soul-friends.

Fate just seems to send them along and we must accept them with all their faults or go without.