Harry had been studying the teachers since he got the aura's on Halloween. Carrow had been one that somewhat surprised him and somewhat didn't. She took great pleasure in humiliating a student, biblically preferably, though she pretended she was just being strict. He had seen her in the mornings her dark aura flaring from recently used Dark Arts. Her quarters, when Harry passed them, leaked dark magic and even her classrooms had it clinging to the air.