Oh, I have no shortage of candidates, I just don't want to turn off the OP by suggesting a pairing they hate.
I could play it that Newt had unrequited feelings for Dumbledore as a student (with possible additions of jealous!Grindelwald spewing suggestive comments).
I could go with Newt imagining Tina or [post-Hogwarts] Leta and feeling guilty about it.
I could go with an established Graves/Newt relationship with or without Grindelwald taking Graves form.
Or it could be Grindel!Graves and a voice kink thing (if OP doesn't mind Grindelwald being vocal).
Just want to make the OP happy (I'll be happy writing any of those... ).
Re: Grindelwald/Newt- Touch Yourself, noncon, masturbation
I could play it that Newt had unrequited feelings for Dumbledore as a student (with possible additions of jealous!Grindelwald spewing suggestive comments).
I could go with Newt imagining Tina or [post-Hogwarts] Leta and feeling guilty about it.
I could go with an established Graves/Newt relationship with or without Grindelwald taking Graves form.
Or it could be Grindel!Graves and a voice kink thing (if OP doesn't mind Grindelwald being vocal).
Just want to make the OP happy (I'll be happy writing any of those... ).