Well Bruce seemed to be able to justify it.
Sleeping with villains, that is.
Really, it hardly counted anyways. Jason wasn't even a villain… sort of. He preferred the term anit-hero when he was in one of his self reflective moods. Dick preferred not to think about it at all.
They would team up sometimes (means to an end and all that bullshit). But things usually broke down sometime after the villains had been subdued and Jason had pulled out his gun. Unfortunately, that wasn't a euphemism. Naturally, Dick had to put a stop to such villainy. And sometimes, if they ended up chasing each other across Gotham's skyline, blood pumping with adrenaline, breaths coming quick and wet on their red, red, lips in the frigid night air until one of them was caught… well Bruce didn't have to know.
That was the one thing they agreed on. Bruce Wayne most definitely did not have to know. Jason saw it as none of his fucking business. If he pushed Dick up against the rough brick walls in a filthy alley way and sucked on his neck like it was his last meal, Bruce had no right to play the judgmental priest to his (deliciously satisfied) sinner.
Maybe it had been about Bruce at first. Maybe dirtying up his perfect cliched golden child was Jason's silent fuck you. And Bruce would never even know.
(Hopefully, that is. Because it stopped having anything to do with Batman a long time ago and now its about heat, and the chase, and Dick, oh my god you are so embarrassing stop it with the puns and the blanket hogging and the weird food combinations.)
Richard Grayson doesn't want Batman to know either. His reasons are as follows: 1) Bruce had absolutely no right to know the details of his private sex life. Ever. (And there was a story there about Kory and the Batmobile and no, just no, Jason, drop it.)
2) If he did know, there would be no way that he and Jason could continue this thing, whatever it was, because if they thought Bruce was good at fucking up his own relationships, they should see him with other peoples'.
And number three was simply that he could guess Jason's reasons and telling Bruce would bring about a certain talk they'd been avoiding about feelings, and intentions, and please don't go again.
Obviously their adoptive (ex) father was on the mind the first time Dick chased Jason down, pinned him to the roof, and let him get away only a little worse for wear. It hadn't even been intentional that time. Totally innocent right up until it wasn't. And really why was Dick complaining since nothing really happened anyways and they both left with their integrities as pure as a liliflower.
When Jason says that Dick just gives him a withering look and a raises an eyebrow and he has to laugh because either of them? And pure? Only if sweet Timothy was secretly a purple hipppomotaous unicorn in a tutu.
Okay. That's weird.
Either way the two of them flee from that roof top with their virtue (heheh), but twice as confused.
And then it just. Kept. Happening.
First Dick is hanging upside down and covered in glitter when Jason happens to be passing by Harley and Ivy's latest robbery on his way to a meeting with some unfriendlies. If it hadn't been for their last encounter he probably would have taken a picture and continued on his merry way. As it is, there's a picture of him smiling under the hood and holding his phone while using Dick's tied, glitterfied body as a handle for some extreme selfie taking taped to their refrigerator. (What the picture doesn't see is the two rogue knocked out on the floor.)
Next it's Nightwing who gets the laugh as he busts in on the Riddler holding Jason above a pool full of sharks. ("Dude, why are you in drag?" "Now is not the time Dickwing!") Sadly there are no pictures of that experience.
And after a while occasional team ups become a near constant thing. "We have got to stop meeting like this." Hood would say when he shot down Cheshire's sai as it spiraled towards his (not quite) brother's head.
And the chasing and the rooftops just continued until someone fucked up and invited the other back home.
Jason. It was totally Jason. "Was not!" Even though he denied it because he was a huge softie on the inside and Dick absolutely knew it. (Jason let's him think that because he doesn't want Dick to see the real damage and just how un-soft he can be. That's not a euphemism either.)
Neither of them entered into their oh god, what is a relationship? with the highest hope or claim to sanity. And soon the near constant my place or yours became our place and the Bat Brats of course found out because where Dick goes they go (and Jason totally doesn't count. Shut up.)
And there was apartment shopping and furniture catalogues and someone shoot me in the head this cannot be happening. All through this they routinely avoided any topics that might set the other off and put whatever this good thing was to a permanent end. (Phrases about gift horses and mouths come into play here.) Topics like that included: Jason's death, Bruce, their shared past as former Robins, Bruce, the Joker, Bruce, and Batman.
The most confusing part eventually came to be how the hell Bruce didn't know that his two oldest sons were living together in the biblical sense. Dick refused to give up his life as part of the Bat Family and Jason wasn't stupid enough to ask. Bruce knew that he had moved and up until then they had assumed he knew where Jason was living too. The two had moved in together half sure that they'd wake up in the middle of the night to see their overbearing mentor and that would be the end of things. He was either seriously slipping or he just didn't care.
Except of course he wasn't slipping and of course he cared in his own bizarre way. Apparently Alfred had run some major interference (and really, like they didn't owe the Wayne butler enough as it was). Bruce had been silently fuming for the first month of Dick and Jason's new arrangement until Alfred had surreptitiously sent an invite for dinner to both Mr.'s Todd and Grayson.
What followed was the predictable identity crisis and freak out (on Jason's part) and the insistence that they go (Dick) and the blowout fight to end all blowouts (both of them) followed by angry makeup sex that had more feelings involved than Jason was comfortable with. And when Jason gets uncomfortable with his emotions there is yet another predictable outcome.
So then Dick had to chase his boyfriend (might as well call it what it was) throughout Gotham in the middle of the night (again) and pin him to a wall in a dirty alleyway and scream at him about his feelings and acceptance and letting go of the past until the sun came up.
And then they went to dinner.