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"A story about a boy who wakes up one day very athletic and gets a necklace that gives him a shield and allows him to travel to different dimensions. He befriends an otherworldly character named Timothy. The book has a lot of combat. His female cousin is also a main character in this. Both of the boy and his cousin are black. This might be categorized as urban fantasy. I remember reading this book in the late 2000s and no later than 2013."