I've seen a number of writers who were capable of writing exactly one character: the person they want to be. It's weird to see two characters who are *said* to have completely opposite personalities *behave* in exactly the same manner.

Like, at some point they become OCs, and people should maybe admit that they want to play with their own dolls rather than try and force invented personalities onto existing characters. And especially when it's an AU, it becomes a case of "this is literally an original work with something else's serial numbers".