You had worked alongside the Hamato brothers (aka the ninja turtles), They treated you like one of them but lately they had been tougher on you and began pushing your limits, going as far as to make you face your greatest fear which only seemed to traumatize you so one day you and Master Splinter came up with a plan as pay back.

Raphael, Leo, Donnie and Mikey were all getting ready for bed. Raph putting on his braces, Mikey putting on his pj's, Donnie brushing his teeth and Leo admiring himself in the mirror. Suddenly they heard a loud boom and went to investigate to find Master splinter on the ground dead, you standing over his body holding a kitchen knife with blood on it. All their eyes teared up and they looked traumatized, before you knew it Leo had you slammed against the wall screaming at you. Raph covering Mikeys eyes and Donnie checking on Master splinter

Splinter quickly sits up "It was a prank!" He says, looking at Leo who has you slammed against the wall "It was payback for traumatizing her!"

Leo's eyes widened, flickering between you and Master Splinter. Everyone seems to calm down a bit but is extremely frustrated and hurt

The next day, no one would speak to you. Ignoring you and walking away whenever you come near, they all hated you right now for doing that to them. This treatment went on for days and Master Splinter couldn't even talk them out of it