TMNT au where Casey is the turtles' regular pizza delivery guy.
He needs the job, and if he sometimes has to drop the pizzas off at a sewer grate to someone who never shows their face and can appear and disappear without a sound, well. Casey's probably seen weirder stuff.
One day there were a bunch of ninjas waiting to try and ambush the turtles, and Casey ran right into them. The turtles prepare to jump in to defend their pizzas (and the delivery boy too...) only for him to whip two hockey sticks out of nowhere and go feral on the attackers.
They talk after the fight, and Casey reveals that he realized they were mutants a while ago, but he doesn't care.
And soon after, a vigilante with a hockey mask and assorted sports equipment joins the boys in battle.
tmnt 2012 au where casey was experimented on by shredder and the kraang to see how mutugen would effect specific things because the kraang wanted to perfect their mutugen and the shredder wanted a mutant army and the reason he needed tutoring was because he was getting reintroduced to humanity.
First post of the New Year! Apologies for December kinda being a barren month, but when you work retail, you have zero life in December lol. So now that things are slowing down, I should have more time!