Black leopard, red wolf
(Book)

Series statement from Goodreads.com

Known far and wide for his skills as a hunter, Tracker is engaged to find a boy who disappeared three years earlier. He usually works alone, but finds himself part of a group searching for the boy. They're a hodgepodge, full of unusual characters with secrets of their own, including a shape-shifting man-animal known as Leopard. As Tracker follows the boy's scent from ancient city into dense forest and across deep rivers, the band are set upon by creatures intent on destroying them. Who, really, is this boy? Why has he been missing for so long? Who is telling the truth-- and who is lying? -- adapted from publisher info