This is from the HP Wiki: "In 1926, Theseus corresponded with Gellert Grindelwald, at the time disguised as Percival Graves, the Director of Magical Security of MACUSA, about recent events in New York, through which Grindelwald (as Graves) learned about Newt."

Um HOLY SHIT. Could we have letters between Theseus and GrindelGraves, please? Especially if GrindelGraves shows an unusal interest in Newt?