Sorry I am late for a few questions.
Well, as Hyena said. I would rather the turtles stay female. It is the main point to the AU. Your allowed to play some one else if you want. A villain maybe? Rat King? Baxter Stockboy- I mean Dexter Stackmen, I am sorry. He has such a forgettable name. Baxter Stockmen. ^^ Lol. Jokes aside, you can also play some one on the side lines, or an ally. Like Irving for example. And an oc is allowed, if you have a good idea to back him up. Other then that, if you want to play Raph. He would have to be the she. I hate to tell anyone who their character is, but this was the idea and I am sticking to it. Female turtles. :(
Empyrean: I have not exactly thought to much on that fact. I so far have a general consensus of the over all plot, but I try not to plan to much since. You players wont magically know my plans. Thus, your x factor may send the figurative wrench through my window, that is my plans. That said, no worries. I will have a idea on how to start. And, Judging by the different characters involved. It would be ultimately different for each. Such as: For the Turtles, perhaps we start with them saving April? Casey can simply start with his origin, why he became a vigilante. (Id recommend watching the Fan made Casey Jones film on youtube. ^^ ) So on so forth.