I don't know why I did this but I'm glad I did because I have many ideas for it.
The fun one of the group. He loves cartoons and video games. Quotes Space Heroes more often than in the show. He always has confetti on him and nobody knows where it comes from. He carries party poppers on him 24/7 and sometimes uses them in battle to surprise the enemies. He's super energetic, kind of dumb, and doesn't take anything seriously (unless he really needs to.)
Leader of the group. He's strict, and takes everything very seriously. He rarely has outbursts of anger, but when he does, you know its serious. He's still super afraid of bugs, and Leo and Donnie like to prank him with fake cockroaches to see what kind of funny reaction they can get from him. Dispite his cold exterior, he cares deeply for all of his brothers.
Super grumpy and super edgy, although he is really a big softie inside. He always has headphones on, as music helps calm his explosive temper. He secretly loves classical music. He also has a love for plants, and could name any plant just by looking at the leaves, although he would never admit it to anyone.
The prodigy of the family, the genius youngest sibling. He loves to create new inventions, although they often don't go as planned. A lot of his inventions tend to blow up in his face. Literally. He doesn't let that stop him, though. He's almost always covered in soot or grease. He also enjoys making clothes for his brothers, their entire wardrobes tailored custom by Mikey.
I'm not quite sure how the other characters would play into this. Casey and April would obviously be switched, as well as Bebop and Rocksteady, and Rahzar and Fishface. As for Splinter, I think I would just completely switch Shredder and Splinter? So that the Turtles would be raised by The Shredder (who has Splinters personality) While Splinter would take the Shredders role. Not sure of Karai or the Kraang, though.