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Almost everything about Rey is purposefully left a mystery. The film strongly hints that she’s related to one of our main characters—but since we get very little indication from Leia, most people think she’s related to Luke. That’s bolstered by the fact when Kylo Ren reads her mind, he sees an island with water. This is a huge clue. Is he seeing Rey’s future, from the end of the film, or her past, when she was with Luke before?