This idea came about some time ago, then only got more inspired when I was rewatching "Singled Out" and noticed Tony and Ziva's interactions seemed more cutting and pointed than usual. So, I speculated. :) No real spoilers in this, just a story set someday in the future when Tony and Ziva have been a couple for a little while.

"It will be fine."

"It's not going to be fine," Tony said, pacing the squadroom. "This is Gibbs we're talking about. By this time tomorrow we'll both be transferred to different agencies. That's if he hasn't decapitated me with a headslap first." He put a hand to his throat. "I like my head."

"I'm glad someone does," Ziva commented.

He glared at her. "This is your fault."

She frowned. "Me?"

"Yes, you. You and your seductive Mossad…sexiness."

"Really?" she asked, somewhat amused. "I am not the one who suggested making out in the elevator."

"No, but your feminine wiles made me suggest it. Vixen."

She rolled her eyes.

"Guys, did you really think Gibbs wasn't going to find out anyway?" McGee asked, watching them from his desk. "It is Gibbs."

"I know," Tony said. "I just wanted to wait until we'd figured out how best to tell him."

"I'm pretty sure catching you two in the elevator wasn't it."

Tony turned to scowl at him. "You're enjoying this, aren't you?"

"What?"

"No, you are." Tony stalked toward him, latching onto a target for his edginess. "You'd like it if I got fired, wouldn't you? Maybe then Gibbs'd promote you up to senior agent."

"That what I should do, DiNozzo?" Gibbs asked, walking to his desk without a glance at any of them.

"Oh, hey, boss." Tony perked up to attention, nervously. "Anything new?"

"Thought you might have something to tell me," Gibbs retorted, still not looking up.

Tony looked to Ziva, who walked out from behind her desk to stand beside him. "Yeah, about that…We, uh…What happened was—"

"Tony and I are a couple," Ziva stated matter-of-factly. "We have been going out for over a month now. I know we should have told you sooner, but we did not want to make a big deal out of it." She turned to Tony and hissed, "Was that so hard?"

Gibbs continued going through papers on his desk.

"We know you don't approve of this," Tony continued over the silence, "Rule 12, I know, but this isn't just some silly little fling. Ziva and I really, really care about each other. And we are going to be together even if it means breaking one of your rules. Boss," he added with a bit less confidence. "Besides, McGee knew too and he didn't tell you either."

"Tony!" McGee protested.

Gibbs sat back, watching them coldly. Tony cleared his throat and got serious again.

"You said not to make the same mistakes you had. To learn from them. And I finally figured it out." He took his empty coffee cup and Ziva's half-full one off her desk. "How do you fill two cups with the same amount of liquid?" He set Ziva's into his. "Put one inside the other."

Ziva stared at him, puzzled, but didn't question the gesture.

"That's your answer you came up with, is it?" Gibbs asked.

Tony nodded, forcing confidence. "Yes."

Gibbs leaned forward, hands on his desk. He looked at Tony. "You've already heard what I have to say about this." His eyes shifted to Ziva. "And you, I thought, knew better."

"I know the argument against dating those you work with," Ziva agreed, "But if anything, my past experience has made me more certain of my choice here. If you are concerned that Tony and I dating will lead to us being unable to work together if we break up, we have already proven that that is not an issue. Tony and I have already been in a relationship years ago."

Panic lit across Tony's face as McGee's head and Gibbs' eyebrows shot up. "Uh, we, ah, what she means is—"

"While you were in Mexico recovering from your amnesia, Tony and I began seeing each other several times a week," Ziva stated, staring right back at Gibbs. "It started as two coworkers meeting to relax after difficult cases, but eventually it became sexual."

Tony choked out a nervous laugh, fingering his collar. "Ah, anyone else hearing that pounding noise all of a sudden?"

"We dated for nearly two months and managed to stay professional enough that no one here even knew it was happening. When you returned and Tony ended the relationship, for reasons I now understand related to the Grenouille mission, I admit I may have behaved a bit…feliney—"

"Catty," Tony corrected automatically, earning a glare from both Ziva and Gibbs.

"Yes," Ziva said, slowly shifting her gaze back to Gibbs. "But I did not let that interfere with our ability to work together then or in the years that followed. So unless you were disappointed in our work then, you should not expect any less of us now.

"However," she continued, "If your concern is that an emotional attachment will get in the way of us doing our job, then your reasoning is ridiculous." When he raised an eyebrow at her this time, she arched one of her own in return. "All of us care about each other more than merely a professional level. Working here has proven to me that that makes a team stronger, not weaker. As for Tony's and my public display of affection, we were off the clock and had already completed our work on the last case, so while it may have been…ill-timed, it was not disruptive."

Tony gestured at Ziva. "What she said."

Gibbs looked back and forth between them for a long moment, standing before him, hand-in-hand without either realizing it. Then he took a deep breath. "Rule 51."

All three agents straightened, startled.

"Sometimes, you're wrong."

Tony and Ziva considered this statement. Tony raised a finger. "So, are you saying we're wrong that we can work together while in a relationship, or that you might have been wrong about Rule 12? Respectfully," he added quickly.

Gibbs sat back and returned to working on the files in front of him. "I guess we'll find out."

"Oh." Tony looked to Ziva with relief. "Well, it's not a 'mazel tov', but I'll take it."

Ziva smiled to Gibbs. "We will not let you down."

"Damn right you won't."

Gibbs continued working silently as Tony and Ziva returned to their desks and McGee relaxed back to his own task. Subtly, Gibbs glanced over at the pair as Tony handed the stacked coffee cups to Ziva, who accepted them and took a sip without removing the second cup. They had been willing to stand up to him to be together. Maybe they had it in them to handle the other challenges they would inevitably face as a couple in this job. Although he wouldn't say it out loud to them, he hoped they did. As long as he didn't have to walk in on them anymore.