Okay, I'm going a little insane.
Found!!!!! By the wounderous @puttingthe-bi-inbittersweet
It's My Way by Whispering_Imp.
There's a fic on ao3 or here on tumblr, about Red Hood meeting and threatening a criminal/dealer, with Nightwing between his legs, clearly cock warming/giving him a blowjob because Dick lost a bet.
The author based it off an image found here on tumblr, adapted from this image here;
Edited to have Nightwing between spread thighs, on his knees, head ducked to imply he's sucking off Jason. I can find neither fic nor image and going insane. No amount of searching has found it by selective 'site search' function.











