The first time it happens, it was an accident.
It was a long shift, but then again, which shift wasn’t in their job? And it had been a while since they had some time for just the two of us, so they decide to go out for dinner. The place they end up is far enough from both the hospital and Robby’s place, so they won’t be recognized by anyone, but still close enough that Robby doesn’t have to drive too much after work.
They find a spot near the back, closer to a window and tucked away from the door, just like Dennis likes. Robby left his glasses back at the Pitt, but he’s too stubborn to let Dennis read it to him, so he’s still looking through the menu, when the waitress comes to their table to take their order. She seems to take one look at Robby’s narrowed eyes and well-humored grumbling, just as Dennis stares at him with a soft smirk on his face—the brat—, and she reaches her own conclusions.
“Ow, is your dad taking you out, hun?” She asks, causing Robby choke on his own spit and making Dennis' smile falter as his cheeks blush. “No need to feel embarrassed. It’s good to see a father taking care of his son.”
Unfortunately, Dennis seems to recover from the shock faster than Robby, because the younger man turns back towards Robby, their legs tangling beneath the table, and flashes a smile that screams danger. “Yeah, my dad’s so good to me. I’m so lucky.”
Robby doesn’t mention how hot under his scrubs that single word makes him feel, and Dennis doesn’t bring it up for the rest of their date, and later that night, when they’ve finally gone home and fall together into bed, Robby has him whining against the mattress, moaning and screaming for his daddy—not his dad, never that.
But Robby can’t stop thinking about it, even long after that night is gone. He had known ever since they started dating that he was older than Dennis, hard not to notice the obvious gap between them, but it was something his younger partner had never complained about, something he had even admitted to enjoy, and Robby chose to not pay it too much attention, for his own mental health. However, it’s clear now to him what they would look like from an outside perspective, and the worst part is that he’s old enough to be Dennis’ actual father.
Maybe that’s why it was so easy for Dennis to call him daddy in bed. They hadn’t talked about that either, and despite Robby’s previous experience it wasn’t something he had explored too much either, but the moment Dennis had whimpered that word as Robby ate him out, they both realized they liked it a bit too much, so it had stuck.
Now, whenever they go out, Robby will wonder if the strangers on the street will see them holding hands, and whether they will think of them as a couple with a big age gap, or a father still taking care of his son—and he tries not to think about why that doesn’t bother him as much as it should.
And Dennis, the little brat, of course notices. He first did at the dinner, and every other time he reminded Robby of how young he was when compared to him, like telling Robby how he liked to have a boy half his age on his knees for him, or casually mentioning how he wasn’t even born when Robby had been in med school.
The problem was when that carried over to the ER. It was an open secret around the hospital that they were together, or at least an ongoing and lucrative bet, but they still tried to keep it low at work. However, Robby, the permanent bachelor and allergic to commitment, seemed to have a hard time keeping up the act around Dennis, and he was always nagging the younger man to take care of himself.
It had been a slow shift, or as slow as it can be in there anyways, and Robby had taken it as his change to remind Dennis of taking a break and eating something. He can’t have his best intern running on fumes for the next seven or so hours, right? But when he had approached the other doctor, Dennis’ favorite protein bar in his hand, the younger man had laughed through his nose and good-naturally rolled his eyes.
That word isn’t a problem by itself. Robby had been working at the ER for too long already, and he was aware he had some sort of… paternal light to him—something he couldn’t quite understand, but Dennis wouldn’t be the first person to call him dad here.
The thing, however, was that it usually happened by mistake, a mix of a chaotic pace everybody scrambled to follow and the sleep deprivation that hounded every healthcare worker, and it always ended with the younger one apologizing profusely. Hell, he’s sure even Langdon did at some point.
But Dennis isn’t doing it as a mistake that can be brushed off easily, they’ve been dating long enough that Robby can see the difference; no, he’s doing it just to tease Robby. So before he can leave and eat his protein bar in peace, Robby stops him with a hand over his shoulder. It’s not that unusual for him to touch Dennis, everyone got used to it after the first shift, but after getting together that had changed—no more casual touches that could be misinterpreted, nothing more than a casual fist bump or fingers brushing as they traded things between a trauma, yet now, with the heavy hand squeezing into the soft muscle of his shoulder, Dennis knows he’s in trouble.
“A word in my office, Whitaker?”
Robby doesn’t leave room for arguments, already moving Dennis’ body through the busy hallways of the ER and towards his secluded and often forgotten office. Robby used to spend a few more hours there after every shift, once Jack got sick of his face and told him to go home, but he never liked to spend his nights alone, so he busied himself with paperwork. After Dennis, is easier to leave this job in time, because he knows there will be someone waiting for him afterwards.
He doesn’t let those soft feelings get in the way as he closes the door behind them. Dennis turns to look at him, eyes big and just a little bit wet, cheeks flushed and lips parted, as if he already knew what was going to happen.
“Ah-ah,” the older man interrupts him, the hand on Dennis’ shoulder moves towards his face, gripping at the sides to turn him towards Robby. “That’s not how you talk to me, isn’t that right?”
Dennis’ eyebrows furrow for a moment, and Robby can’t tell if he’s being genuinely oblivious or faking it just so the punishment will be worse. “…Daddy?”
Robby sighs, “c’mon, sweetheart, you know better than that.” Dennis’ gaze turn unfocused, the same way he does whenever Robby manhandles him too much in the bedroom, leaving both mind and body into his hands. “You have been teasing dad all week, haven’t you?”
He finally stops holding Dennis’ face, leaving the younger man standing alone as he rounds the desk in the middle of the room and sits behind it. Dennis keeps track of him, swallowing heavily when Robby spreads his legs. “Sorry, dad.”
That day, Robby finds a new use for his usually empty office, and they both find something new and exciting to explore.