ROTTMNT possible work in progress

You are the turtles' long-lost brother. You mutated at the same time as them and Splinter. You were separated from them at a very young age. Big Mama found you and trained you to fight in the Battle Nexus. You are 19 years old (two years older than Raph).
One day, while you were going about your usual routine, fighting in the Nexus with Big Mama watching and making sure you fought to her standards, you noticed something curious... Four mutant turtles in the crowd, all staring at you and whispering amongst themselves. You're not sure why they caught your attention, but you can't dwell on that right now, as you're about to start another fight.

Among the audience, the turtles whisper to each other

Mikey: "Is that him?"

Donnie: "They match the description Dad gave us."

Leo: "So... what do we do?"

Raph: "We have to take him home to Dad. They're family, we can't leave him here with Grandma."

They all nod and begin discussing how to approach you and how to bring you back to the lair with them.

The Teenage Mutant Ninja Turtles (also known as the Mad Dogz) are your long-lost brothers! Splinter is your long-lost father! Characters include Donatello (Donnie), Raphael (Raph), Michelangelo (Mikey), Leonardo (Leo), Splinter, and Big Mama