I've been seeing quite a few Graves/Newt soulmate prompts around where Newt knows Graves isn't the real Graves because polyjuice can't replicate the soulbond.
But what if it did, at least in part?
What if polyjuice copies everything from the original person, including soulmarks/soulbonds etc. For most people when they revert back to themselves their own bond overpowers the temporary one made when under the potion. But Grindelwald is one of the few who doesn't have his own mark so after he triggers Graves and Newts bond he doesn't have anything to override it when he becomes himself again. So while Graves and Newt are definitely soulmates, Newt and Grindelwald kind of are as well now and no one knows quite what to do.
Bonus points for Real!Graves in captivity seeing/feeling his soulmark activate and knowing Grindelwald is with his soulmate.
Real!Graves/Newt/GrindelGraves - Accidental soulmates
But what if it did, at least in part?
What if polyjuice copies everything from the original person, including soulmarks/soulbonds etc. For most people when they revert back to themselves their own bond overpowers the temporary one made when under the potion. But Grindelwald is one of the few who doesn't have his own mark so after he triggers Graves and Newts bond he doesn't have anything to override it when he becomes himself again. So while Graves and Newt are definitely soulmates, Newt and Grindelwald kind of are as well now and no one knows quite what to do.
Bonus points for Real!Graves in captivity seeing/feeling his soulmark activate and knowing Grindelwald is with his soulmate.