Casey was no longer herself without her other half. She had not realized she was dependant on her string bean of a cousin until the girl was gone. Never know you love her 'til you let her go. Lily was safe, now, back at home with her brothers to take care of her. Casey was certain that they could not take care of her the way she did, but... then again... her confidence was shot. Besides, it had been under her watch that Lily had gone missing, had dropped out of school, had suffered. Casey had failed her cousin, and now she was missing her.
And you let her go.
The loss had affected her greatly. She had become a lone wolf at Hogwarts, keeping little to no company, and biting the head off of anyone who tried to become company. She was an angry little girl, and her family seemed to have forgotten that this Lily business had a lot to do with her and she probably needed some monitoring. They'd be finding out when someone lost a limb.
She came into the library and immediately sought out her usual spot. As she approached, however, she saw that someone had taken the spot. She approached slowly, trying to keep herself cool. She just had to move them. That was all. She loomed over the girl, barely. Casey was short, even if the girl was sitting.
"This is my spot," she said pointedly.