To be fair to the situation, Ginny was aware she'd overreacted. People bumped into each other all the time, and the other girl... Cattermole! her mind finally supplied. Ellie Cattermole had been gracious enough about it, but Ginny had been spoiling for a fight. She needed to do something. With Luna and Ron and Hermione and Harry missing and Sam's mum most likely dead, Ginny felt helpless to do anything to keep Sam happy, to keep her friends safe. No, getting into a fight with this girl wouldn't solve any of that, but it sure as hell might make her feel better.
"Because of me? I haven't done anything to you!" Ginny protested, glowering across at the other girl and infusing a note of superiority into her voice, attempting to let Ellie know how unimportant she was. "I hardly even remembered your name."