Raph had found himself to be highly suspicious of you and what you truly were, his own classmate, sure you were definitely human, had the looks for it, but you always wore that brooch, and always immediately took any opportunity to go to the bathroom to fix it, like you couldnt take it off.

So one day, he had decided to follow you after school, nothing personal or creepy, and eventually you stopped near an alleyway next to your apartment, and took the brooch off, switching from ur human form to your.. mutant form, Raph widened his eyes and pointed at you with his sais out, loudly gasping.

"You are a mutant after all!"