Doctor Whooves (The Doctor) has had a good and long run through time and space with Ditzy Doo. But it is that time again for him to regenerate bodies. But this time, it seems... different... What would happen if The Doctor regenerated... As a mare?
Derpy Hooves has D.I.D. But this is a special case. Most D.I.D. ponies are unaware of what their other personality does. This is not the case. This one pony; with three different minds; saved Equestria. This is what she did...