This is part of the "I'd Take Imperfect Any Day" canon, taking place a few months before that story.
Even before he landed onto the building a block away, Jason knew he was in for a fight. And it was going to be a doozy. Because every fight they had had so far got a little louder every time. So yeah, he figured he might as well be comfortable when it happened. He manage to get his helmet off and pull out his pack of cigarettes before she could catch up. He heard her feet hit the rooftop.
"Are you crazy?!" she shouted from behind him before her grappling hook was even snapped back onto its holder.
"Oh probably," he said, the cigarette bobbing between his lip so he could get out the lighter as she stomped up to face him, her hands balled up in fists of fury.
"You shot the guy in the kneecap!"
"Better than his head, Batgirl," he muttered with wavering patience, the words pushed between mostly firm lips as he tried to keep the cigarette in place long enough to light the damn thing. Damn lighter kept clicking.
"That's it?" Barbara continued, scoffing. "'Better than his head?' That's really all you can say for yourself?!"
He sighed. He liked Barb. He really did. Probably the most out of all the Family and not just because she was the main focus of his very vivid sexual imagination throughout puberty. She was smart and diligent and maybe part of him was excited about working with her. And there were times when things were going great. Really great. She was really funny when they were on stakeouts — he quickly remembered why she was so much fun to work with back during the Robin days. And then moments when their hands would graze and she'd hint at a smile or she'd look at him like she was thinking something over and he'd wonder …
But goddamn it if working with her was driving him crazy. Mostly because she was judgey about everything he had done on this mission and she made every gunshot into a big thing and then he'd retaliate and holy crap, why was everything so tense! Oh, and then she's walking around in her Batgirl outfit and oh yeah, that's not already a turn-on for him left over from before he died or anything.
Why Kory even suggested him working with Barbie, he couldn't figure out. Maybe just to get him out and about now that Kory was dating Dick. Oh right, he was trying to remind himself not to think about that little "best friend is dating your pretty boy brother" development.
Why won't think damn thing light? Jason thought as he focused on the lighter in his hand to avoid the furious redhead in front of his face. That was when she snatched the cigarette out of his mouth.
"Hey!" Jason said, reaching for it. But Barbara turned and tossed off the roof.
"Barbie, what the hell!" he said, officially pissed, "that was my last one!"
She ignored the name slip, choosing to stare him down instead. "Shooting him was totally out of line and you know it. Do you really want to be a monster like them?"
"That's how I do things, Batsie," he said, leaning over her, "if you want to run with the big boys—"
He saw arm move just in time, catching her wrist with his hand before her fist hit his face, their faces suddenly incredibly close to one another.
"You think you scare me, Jason?" Barbara said, the tension gritting in her voice, "I can handle you and your little temper tantrums."
"Get off my back, Gordon," he said with a growl at her name.
"Make me," she snarled. Maybe it was the fire in her eyes. Or how her stupid ruby red lips were just inches from his. Or maybe because the thought had crossed his mind a bajillion times over the last month. But something in his brain clicked and nothing made more sense to him than to bridge the minuscule space between them and kiss Barbara. Which he would have done if Barbara hadn't pulled his neck down and kissed him first.
Quickly he had her pressed against the brick of the rooftop stairwell, her arms around his neck and her gloved hands gripping the back of his hair and her right leg hitched up his hip. It just felt right to press his left thigh firmer between her legs. She shifted her hip so that her core rubbed against that thigh and her own leg pressed against his groin.
"Barrrbie," he moaned, dragging his mouth across her jawline. This was way, way better than that peck he stole when he was 13.
"My place," she gasped, still grinding on him, "Two blocks away from us."
Jason moaned harder as a brilliant vision flashed through his mind of Barbara bent over a bed, legs spread wide as he sank into her. If he hadn't had an erection already, that flash of possibility certainly did it.
"Is that a yes, Hood?" she muttered with a breathy smirk, clearly knowing exactly what she was doing to him.
"That's a fuck yes, Batsie," he practically growled against her lips before dipping into for another kiss.
With a bite to his lower lip (that went straight to his cock), Barbara got out two blessed words: "Follow me."
Approximately five minutes later he was in Barbara Gordon's apartment. In her bedroom. Between attempts to stripping him down to nothing and peeling off her damn suit, he pressed her against the wall, she pushed him onto the bed. It was rough and messy and fucking exquisite. Everything he had imagined in his wildest teenage boy imagination. And when she finally came, a gasp on her lips and her nails gripping his back, Jason decided with his last coherent thought that his measly teenage boy imagination had had nothing on the real thing.