Spencer was such a pragmatist. William eyed him, but couldn't actually argue with that logic. Still: "She's after me," he confided darkly. After a brief pause to listen, he cracked the door open enough to let a tiny slice of light through and cast a periscope charm. It snaked out and around the corner, showing them Hayley, still loitering in the hallway talking to a pair of students. Holding her clipboard.
"She must know I'm here," he whispered to Spencer, volume level dropping steeply now that there was visual confirmation of Hayley in the very room (cupboard) with them. "Do you see where she's standing? In between the library and the staff room, Spencer. In between us and the tea."
She was clever, he had to give her that. But then, there'd never been any real question of why Hayley'd been Sorted into their House. William only regretted that she'd clearly chosen to use her powers for evil.