Princess of darkness and crows.

From the outside looking in Raph looks like this violent person who's just anger and rage and is suppose to be a parallel to the Shredder. But really Raph is a big softy. Whenever end of the world shit happens or did Raph is usually taking care of someone and trying to help people. Yes with some butt kicking and weapons involved. But rarely does Raph become and out right villian(and if he does mind control is usually involved). Raph is realistically the softest turtle of his brothers. If he lost his brothers and the world went to shit, Raph is depressed, suicidal. But hes still trying save people and stop bad guys. Now his brothers on the other hand, Mikey if he lost his brothers gets really close to the edge of super villian. But mainly he just wants to die. Kill the thing that killed his brothers and than die. Because he cant handle being alone. He gets really gray in morality and goes full on becoming the best ninja out of his brothers now that he has a proper motivation to be the best. But he doesn't go full super villian. But he's not Mikey anymore either. He's lost that. Now Leo and Donnie on the other hand if they lost everything. They go full supervillian. No stops all the way, burn the whole world down because the things that kept them kind( their brothers, their family, master splinter, new york, but mainly their brothers) are gone. From all the stress of their daily lives of being the leader/oldest and being the one that kept their brothers alive with his genius. Their biggest fear actually happening in front of them, and they couldn't stop it. And they had to keep living afterwards. Yeah no they are becoming super villians. And if those two where the last ones standing together, yeah they burn down the whole world together. They would become totally on board with being super villians together, because fuck the world that took their brothers. They where kind before, but now now they don't give a shit anymore. We gave the world everything, and you took the only thing that was theirs. Leo and Donnie if left alone would definitely be the ones to become super villians out of all four brothers. Depending on which I cant tell out of the two of the would be better at being a villian. But if it was them being a duo villian squad. Yeah the world would have no chance. Leo and Donnie choose to be honor, to be kind.