After losing both his mother and his father, due to a group of villains attacking his home, a young Sly Cooper is sent to a nearby orphanage with his family's cane in hand. There he finds Murray, Bentley, Gilda, and Derpy Hooves, the four people that he would eventually come to call family one day. Together they practice their individual talents and pull off some successful heists, all while searching for clues as to the whereabouts of the Fiendish Five, the people that took out Sly's parents... as well as recover the pages of the Thievius Raccoonus.
All of them must deal with the tests and challenges that come with being in a gang of thieves, especially when some tests will push them to their breaking points.
(Sly Cooper/ MLP crossover)
(Part of the Universe 13 story series, though reading the other stories is not required)