If she could, Mandy would live in the library. She was fairly certain she spent more time here than in her room, and even then, it was often hard to get her to leave the library for food. Even harder at night, once the library was closed and she was expected to return to her dorm. Each night she would be asked repeatedly to leave because she had never understood the point. The library had books, an infinite source of knowledge and power, and she would happily sacrifice a warm bed for that. She had already given up any semblance of a social life. Her path to greatness and success began here and in the classrooms, not in her room listening to her roommates gossip or watching her fellow Ravenclaws play chess or listening to a 6th year whine about potions. But Rules were Rules, and they were made to be followed, not questioned, so Mandy resigned to only spending her days here.
Noble ambitions aside, it was easy to distract herself here. There were books to get lost in, and she didn't have to worry about how it was becoming increasingly likely that they were all going to die here. Or just lose their magic, maybe, but that was just as bad in her mind since it meant the same thing: that all of this hard work was for nothing. But for once she's not being pessimistic, and she was happily reading her history book, quill poised above her parchment and ready to take notes.
She hadn't meant to look up. She couldn't say with any sort of certainty what compelled her to glance up from her text. But for whatever reason she did, and it was then she spotted that Slytherin boy. James maybe? Jordan? But the details weren't really important, because he looked vaguely nervous, which she took to mean that he was breaking the rules, the very rules that she held close to her heart like one would a lover. She had no reason to suspect that he was doing anything wrong- it was more likely that he had a test to study for, and he was simply worried about that- but Mandy usually assumed the worst until proven otherwise so her eyes just narrowed as she surveyed him disapprovingly for a moment.
And then she spoke to him- Julian, that was his name- with all the authority she could muster. "Don't you have class?" No, she shouldn't have phrased it as a question; that would make it easier for him to lie, if he was in fact cutting class, but it was too late now. It didn't really matter that she had no reason to accuse him of anything; he hadn't done anything to her, and as much as she liked to think otherwise, she wasn't a prefect so she really had no authority over him.