Post-film, Graves is rescued and goes back to work. Somehow, he gets injured while on a case, and ends up in the hospital. Grindelwald (who's escaped by this point, because, let's face it, he was probably in custody for all of 24 hours) pays him a visit. Graves, too injured to even move around that much, can't do anything about it.

Note: I'd prefer no rape (as in penetrative sex). That being said, nonconsensual touching is still on the table.