Takes place around the whole movie. Newt knows the real Percival Graves. He married the man, had been for years. Ofcourse he would know what he's like. He doesn't keep Graves wedding ring with him otherwise. It's a promise that he would always come back to return it to him. And becomes very suspicious with the lack of response.

Because Graves is the head of magical law enforcement, he keeps his marriage a secret to keep Newt safe from being a target. Newt understands that Graves might be an imposter at some point. So they came up with a code phrase between them.
Newt would offer Graves a tin of chocolate chip cookies and asks "would you like a Biscuit?" Which Graves hates. His response will always be, "where are the Snicker doodles? " Graves security question is, "Out of all the roads you've traveled, which one is your favourite?" Newts answer, "The one that brings me home."
Grindelgraves fails this. He ate a Chocolate chip cookie. And his cover is totally blown. And now all the Aurors are searching for the Real Graves.

Bonus if Newt and Percival have matching boxes that transfers letters instantly, engraved with various animals.

+bonus Gramanders apartment is trashed from Graves and Grindels struggle. Newt notices that all of the items with his name a distroyed. (For his protection)Like the calender that has all of Newts departures and arrivals.

++bonus The box can only be opened with one or both of the wedding rings. And Graves is locked inside while he was trying to sent a note saying "Don't come ho... (home)." In his fight with Grindlewald.

Sweet ending with cuddles in the hospital.