Emerald Slytherin was a pure-blood witch, the younger sister of Salazar Slytherin, co-founder of Hogwarts School of Witchcraft and Wizardry and a ghost of Slytherin House. She attended Hogwarts as one of the first students and was sorted into Slytherin, where she taught Potions. During her time at the magical school, she befriended Helena Ravenclaw. At some point after starting her education, Emerald stole her brother's staff in an attempt to make herself unique from her brother instead of just being known as "the sister of Slytherin" and ran away to Black Forest. Her brother eventually left Hogwarts but, after becoming fatally ill, he returned to the school and, hoping to see his sister one last time, sent Minverin Pertran, a man who harboured an unrequited love for Emerald, to find her. In a fit of rage, the Minverin murdered her when she refused to return with him, before he committed suicide out of regret for what he had done.
Emerald and the Minverin eventually returned as ghosts to Hogwarts Castle, where she became and continues to be a Ghost of Slytherin House.
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