Grindelwald (not disguised as Graves) forces Credence to watch as he takes his beloved Graves against his will. Credence knows it's evil and sinful but he can't help but get turned on. Grindelwald notices Credence's dilemma and invites him to join. To Graves' surprise, Credence willingly accepts

+ if Graves is a crying sobbing mess, utterly humiliated by Credence seeing him like this
++ if Credence cries and apologizes throughout
+++ if they spitroast him