Grindelwald (as Graves) thinks Credence is lying to him about something to do with the child, maybe trying to protect one of his sisters.
So he slips some veritaserum into Credence's drink (during the infamous diner scene?) and questions him, only to find that Credence had been telling the truth.
But Credence is still under the effects of the potion, and Grindelwald is feeling devious, so he begins questioning Credence about a bunch of kinky stuff, what he fantasizes about, how often he thinks about touching himself--how often he gives in and does it, how badly he wants Mr. Graves to touch him, etc. etc.
+ Credence crying from how humiliated he is ++Grindelwald making Credence touch himself right there at the table until he comes while spilling his deepest darkest secrets (Credence doesn't know about the disillusionment charm and is under the impression that anyone else in the diner could notice him doing this at any moment)
Grindelwald/Credence veritaserum...kink?
So he slips some veritaserum into Credence's drink (during the infamous diner scene?) and questions him, only to find that Credence had been telling the truth.
But Credence is still under the effects of the potion, and Grindelwald is feeling devious, so he begins questioning Credence about a bunch of kinky stuff, what he fantasizes about, how often he thinks about touching himself--how often he gives in and does it, how badly he wants Mr. Graves to touch him, etc. etc.
+ Credence crying from how humiliated he is
++Grindelwald making Credence touch himself right there at the table until he comes while spilling his deepest darkest secrets (Credence doesn't know about the disillusionment charm and is under the impression that anyone else in the diner could notice him doing this at any moment)