You’re all in the turtles’ lair after having defeated the Kraang. You weren’t supposed to help them. You’re the child of Shredder, yet you just helped the people who defeated him last time defeat him again. That’s fine, though. You’ve never liked your father much. You were always going against him, no matter what. You were mutated by Eric Sacks as well, just like the turtles, except it was for Shredder, as a gift to him. You are a Shiba Inu, just mutated and more humanoid.