Familiar Path — A.M. Burns

When Lugh McNeal turns fifteen, his life turns upside down. Following an urgent call for help, he rescues a young cat from the river and discovers a family secret he never suspected. The McNeals are magical. Now, with his new familiar Bran, his cousin Abby, and their friend Wyn, Lugh must figure out how magic works before the forces that seek to destroy them can get the upper hand. When Abby and Wyn are kidnapped by the dark Magus, Lugh and Bran rush to find them, but have they learned enough to walk the magical paths?