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The Emerald Trio. Harry's cousin, Ron's other sister, and Hermione's sister. They are all good friends. Kinda ??? fandom x Harry Potter crossover fanfiction. The Emerald Trio were left in Grimmauld Place by their siblings. They escape. When they were out, they went to a cafe. Ron's other sister gets a note. The Avengers happen to be at that cafe. What happens???