Severus has picked his pencil back up. He's turning it, sticking one end against the table, pressing down, picking it up, turning it over again - it's a habit that betrays just how irritated he still is. He'll have broken it by the time Harry is his student, having settled into his graceful and intimidating persona entirely, his work as a triple agent having worn away the distinction of who he is. For now, he's still something like a real person.

"I know," he says quietly, about other people on the ship. Watching Harry closely. "But I don't think that's what Lupin meant." He knows it's not. Instinctively. His gaze doesn't waiver from staring at Harry.

"I don't mind teaching you. I mind helping you and then having you turn around and lie to me."