It seemed a little too easy when Newt used Revelio on Grindelwald (you would think that Aurors would use that spell often enough that Grindelwald would have been revealed earlier, y'know?) Which got me thinking, what if Grindelwald hadn't used polyjuice or transfigured himself, but instead had possessed Percival Graves? If Grindelwald hadn't been revealed then, how much more damage could he have done?

And eventually if Grindelwald was defeated and Graves was freed, how would Graves recover from having had his body and mind taken over for months, watching everything that Grindelwald did without being able to stop it?

I'm partial to Graves/Scamander and Grindelwald/Graves but anything goes, pretty much.