"The mutual forces of action and reaction between two bodies are equal, opposite and collinear"

Newton's Third Law of Motion

The change is like a slow deadly cancer that gets under her skin after too many years of exposition. Quiet, patient, this cancer… this change, it slips into her pores after too much sunlight… too many blows, until she is soaked wet in it. One last day of intense sun… one last deep betrayal is all it takes for it to be too much, and soon enough, there is no longer room inside herself for anything that is not this new her that has eaten the old one alive. It hadn't been a loud violent death in a storm of angry shouts but a quiet retreat in-between silenced whispers.

Sometimes Ziva wakes up in the morning and looks at herself in the mirror for minutes, trying to find something that isn't there anymore. Sometimes she lets herself miss it with such nostalgia that when it waves through her it leaves her trembling. Most of the time she just convinces herself that she hasn't lost anything that anybody considers worth missing, nothing that anybody would actually miss. Those days she scrubs her face skin clean, smiles a little smile and keeps going with her day as it were paradise on Earth.

Tony arrives to work every morning with a mix of anxiety and hope that is often mistaken for hunger. He takes his time, every single morning, to spy on his partner with studied casualty. He searches for her in between bad jokes and film quotes and he covers his disappointment at not finding anything other than this brand new Ziva-shaped shell with pop culture references and bad coffee.

He misses her with a force that makes him angry and gets him irritated for the rest of the day. He misses her, every single day.

He is interviewing the victim's neighbour when he hears Ziva shout and start running after someone, so he politely says absolutely nothing at the old men he is interrogating, lets his notepad and expensive pen drop to the floor and starts running after his partner before any of those things can touch the ground.

He runs until he recognizes Ziva holding her position against a wall around a corner. Two feet to her right, old shoes, pizzas boxes and all kinds of crap fly out of the alley entrance.

"What are we doing?" asks Tony almost in a whisper, almost out of breath.

"The suspect got into that no exit alley"

"And are we waiting till he runs out of garbage to throw at us?"

Inside de alley, the suspect keeps calling her all kinds of gross, rude names as loud as his lungs will let him.

"I was waiting for backup" she answers giving him a quick glance.

"Why? Are you suddenly scared of dirt?"

"I was just following the procedure"

For a moment or two, he can't really believe what he is living, that is, until the contents of a disposed soup can hits his most expensive trousers.

He tries to get her to fight back.

He launches piece of banter after piece of banter at her, until it becomes heartbrokenly clear that he is not going to get a reaction out, that it's all useless. She has lost her edge, her revengeful ninja style. She has lost her mysterious mesmerizing little smile.

She tries to hold herself back.

Life has seen to make her understand that when you fight, people may kick back harder than you can deal with. If nothing else, she has learned that lesson and so she stops overreacting for everything and death-threatening people with office appliances.

Safe mediocrity is the best she can hope for these days.

They are both at their designated desk.

"So I heard that your boyfriend is coming over this weekend."

"Yes, I plan to make an official introduction at McLarens."

"Such a pity, I have a previous engagement."

"I didn't tell you when it was going to be."

"I guess I'm a pretty busy guy."

They don't look at each other through the entire conversation.

He never learned to live without his partner; not before Somalia, certainly not after it, that doesn't keep him form trying, nevertheless.

He starts with the occasional drink at the occasional bar and when that doesn't work he insists and tries more desperate measures; he kicks up the practical jokes and stops the grown up conversations with her. He goes back to his flippant silliness, to flirting around shamelessly and sleeping around as much as he can, which at his age, is not only starting to become pathetic but also far too much like Anthony Dinozzo Sr. for his comfort.

He looks at himself in the mirror every night and welcomes the change, observes the reflection knowing that he is becoming a joke of himself and smiles. Maybe, if he changes completely, if he can also become a shell of who he is, of who he was, he will stop missing her all the time, missing them.

Ziva watches him as he crosses the hallway blatantly lusting after a young blond agent. He looks like a cartoon, with his exaggerated easy-going ways and his fast movements that get McGee to attempt to elaborate punch lines at Tony's expense.

This is their new dynamic; Tony fools around, Ziva admonishes him, Tony leaves to fool around somewhere else, McGee and she make fun at him. She thinks that this is an easier life than the one she had before and that has to be good, yeah, they all are happier now, even if she doesn't feel it in her bones.

They gravitate towards a bar, or more specifically she gravitates towards a bar and he ends up gravitating towards the same bar.

She sits at a stool; he seats at the stool next to her and doesn't order a drink. Minutes pass and she lowers her head and sighs loudly.

"He is a good guy," he hears himself saying out of nowhere. "Ray. He is a good guy." She almost smiles sadly.

They resemble somebody else, somebody they were a couple of years ago.

"It doesn't matter. He lied to me."

"He is CIA, Ziva, what did you expect?"

His voice doesn't sound as harsh as he intents to, 'cause really, by now she should actually know better than this, maybe he should too.

"It was just a bad idea."

"Understatement of the year."

"Oh, and dating a co-worker isn't?" she bites back, as if there were an implicit betrayal just there.

"You'd be surprised of how uncomplicated it is compared to other co-worker's interactions."

"Closeness, usually is complicated, Tony," she uses her best I'm-talking-to-a-child-here tone of voice that she knows he hates so much.

"We are not close." It comes out too much as a practiced retort, not that it matters to any of them.

She turns around to look him in the eye before continuing with the conversation.

"Stop saying that we're not close," she says matter-of-factly, putting an end to all jokes, if there were actually any. "We are. We're family."

"I don't particularly like my family, Ziva, I definitely don't like yours."

"That doesn't change the facts. You're like my brother."

"Stop saying that I'm like your brother," he sounds particularly offended.

"Tony…"

"Your brother killed my partner. I'm nothing like your brother."

She regrets the words a moment before saying them, but it doesn't stop her from letting them scape her lips anyway.

"Well, you killed my ex-partner, so maybe you are."

After that, it's all been said and done.

They both say mean, harsh, rude things to each other and they both succeed at making them pass as well-meant jokes between partners. They become proficient at the noble task of looking unaware of the existence of any problem between them. They have finally got to change so completely that to the common eye they look just like any other pair of public employees randomly chosen, like Gibbs and the janitor, like McGee and the crazy chic in accounting. Two completely indifferent to each other co-workers, as if this polite forced distance and studied ignorance wasn't consuming almost all their energy on a daily basis.

Ziva still stares at her reflection in the mirror from time to time. She almost doesn't remember what she looked for in it before. She still scrubs her face skin clean and keeps going with her day.

Tony still leaves the office every day with a strange feeling in his gut. He almost doesn't remember what he misses so much.

They have become experts at the fine art of deceiving themselves, but they haven't realised yet how to stop hurting.

One morning Gibbs stops in his way to a much needed caffeine refill and stands in between their two desks.

"You two," he says signalling them alternatively with a pointed accusative finger, "-sort it out."

He goes away and leaves them mutely staring at each other like they are merely acquaintances that have absolutely no idea of what Gibbs is talking about.

The shit hits the proverbial fan the day Tony doesn't show up for work, he is not answering his cell phone either, nor his house phone for that matter. He is not at his apartment, nor at Barrets' apartment; he is simply nowhere to be found.

Echoes of the Port-to-Port Killer are in the minds of everybody even if nobody wants to voice it out and Ziva… Ziva feels like she is falling down a spiral with no end in sight. Her breath catches in her throat and has to fleet to the bathroom to splash cool water on her face before losing it completely.

It doesn't make sense, doesn't make any kind of sense at all. She has been a good girl lately, a by-the-rules girl, an under-the-radar girl, a quiet, disciplined girl and still, once again, somebody is kicking her harder than she might be able to take.

The reflection of her dripping face challenges her from the other side of the mirror."What are you going to do about it?" it seems to say, and Ziva feels the rush of red fury fluster her checks and fire up her eyes.

To hell with it. She squares her jaw and makes fists with her hands. If the powers that be aren't keeping their part of the bargain she isn't going to keep hers either, she is going to kick back, hard, as hard as she can muster.

"If you're not dead yet, you can get out of it stronger," her reflection insists.

All her muscles tense up and she lifts her chin, a long lost light back into her eyes. She is nowhere near dead yet, and as for whomever that has taken Tony… she can't say the same.

He wakes up to the smell of antiseptics and a heavy and insistent headache that spreads around every neuron in his brain and screams "chloroform". He opens his eyes and can barely contain the grunt that forms in his throat when the daylight hits him.

Hospitals are so much fun.

At the not so distant end of the room, someone looking out of the window blocks part of the sunlight. It's not hard to recognize the crazy wild waves of her hair even if it has been a long time since the last time she went to work without having straightened it first.

"What happened?" his voice is hoarse and his lips are dry.

Arms crossed over her chest, she turns around slowly and takes two steps toward the bed, moving away from the window.

"Seems like the Port-to-Port killer wanted to play with you and doesn't know how to ask nicely," she takes another step, worry written all over her face. "He got away but we managed to get you."

He groans and a sharp pain cuts through his chest. A broken rib, probably. Maybe two. He takes a quick glance around the room and notices empty cups of coffee, Abby's dear hippo, an ugly flower arrangement and the clock at the wall in front of him that marks the day as well as the hour.

"Shouldn't you be working?" the words come out lazy and low.

"Not really, I'm on probation."

"Probation?" his voice squeals "What did you do?"

She smiles. She smiles that mysterious mesmerizing little smile of hers that Tony knows means she has kicked serious ass.

"I did what I had to do. Don't worry, I got your six"

He wants to keep looking at her, at this Ziva of bright ninja eyes, fearing that if he closes his eyes for more than two seconds she will disappear again, but he is too tired and too doped to keep his eyes open.

The darkness blissfully embraces him and he feels her hands wrapped around one of his in their tender warmth.

"I've missed you," he says from the edge of consciousness.

"Just rest, Tony," are the last words he hears before falling back to sleep.

Like the riverside after a flood, they have to grow up again to who they were before and, like the metaphor at hand, the process is slow and hard and more often than not, also awkward and silent.

He doesn't get the uncomfortable feeling in his stomach (often mistaken by hunger) every morning anymore but instead feels a different kind of anxiety every time Ziva gets close enough, as if whichever room they are in doesn't contain sufficient oxygen for the two of them.

Her eyes, alive and passionate like before, contain a new kind of intensity now, a deeper wisdom and overcome sadness that threats to swallow him whole and he wonders, if he looks as old as he feels.

Like the riverside after a flood, they can't be exactly the same they were before.

Tony's up for office duty soon enough but going out in the field is absolutely forbidden as anyone who crosses paths with him insists on manifesting.

He gets to stay and guard the fort every time the boss tells them to grab their gear and he acts like it doesn't bother him at all, like it is some kind of paid vacation with a lot of phone picking involved.

From across the bullpen E.J. looks at him occasionally and smiles at him, and that smile builds a slight gulp in his throat, the performance suddenly too hard to maintain.

The elevator arrives to the floor and the muffled voices make him forget himself. He stretches his neck in a fairly good impersonation of a meerkat and watches Ziva roll her eyes at whatever McGee is bitching about behind her as they come nearer.

"Enough of the wine McGee" she says and McGee looks at him confused in search of appropriate help.

"I think she meant 'Enough of the whine'," he makes a pause for the effect, "McWine".

He gets up and walks towards Ziva with a yellow post-it in his hand.

"Ray has called. Again," he says sticking the note in the middle of her computer screen. "Tell him I'm not your secretary"

"You can tell him yourself if he calls back," she says making eye contact, "after all, I know better than to get involved with someone who lies and has a secret agenda for a job. Again." She smiles like there is a secret meaning in that sentence that only he can decipher.

Maybe it is.

He is still smiling back when Gibbs appears out of nowhere to slap him on the back of the head as he passes by. "Good boys" he says in a small voice.

Instead of falling back to seriousness, Tony's smile just gets broader.

The uncomplicated, easygoing, convenient relationship with E.J. suddenly becomes a bunch of eggshells he is afraid to step on all the time. He watches Gibbs disapproving looks at E.J., E.J.'s resentful stares at Ziva, and the exasperated glances Ziva's shares with McGee, all in quick succession as domino pieces falling around him.

It makes him cranky, nervous and tired, like he doesn't really belong anywhere anymore.

At work, he takes any excuse he can get to hide at Abby's lab, drinking from her contagious, everlasting good mood.

At home, he looks at himself in the mirror and watches with worry the wrinkles get deeper around his eyes.

He looks for peace, the kind of overwhelming peace he found in his own features when he first came back from Africa, but it's no longer there. What isn't there either is the unhappy, passionless façade he has come used to see in himself in the last months.

Halfway here, halfway there.

Maybe he doesn't know how to be happy just yet, but he certainly is improving at figuring out the things that surely make him miserable.

They meet for a quiet dinner at a nearby little Italian restaurant, it's not like they can meet much more with him still without the full recovery check.

Her long blonde hair and blue eyes obscure as soon as they enter the place, the mildly lightened restaurant is loud with operetta music and relaxed laughs.

They sit and start to eat in the middle of the same tense silence they seem to be unable to avoid lately and Tony, mutely thanks the insistent background noise for nicely covering it up.

"I think Ziva has a crush on you," she says as she rolls her spaghettis around the fork.

He snorts more out of surprise to hear E.J.'s voice than for the sentence itself and prepares his trademark gigolo voice before answering, "I tend to have that effect on women."

"I'm serious Tony, you should have seen her when you were taken. She beat the crap out of a guy twice her size for information."

He can't quite make out the expression on her face but can distinctly hear the annoyance in her voice.

"That's not exactly out of the ordinary," Tony dismisses and takes his glass of wine hoping for a change of topic.

"He could have led us to the Port-to-Port killer, you know, if we hadn't had to release him thanks to that"

"And that's why you think she has a crush on me?" he says incredulous like maybe it's some kind of joke and sips from the glass.

"No, that's why I think she is in love with you. I was just being subtle."

The aggravation in his gut matches the one in her tone.

"She is not…" Tony interrupts himself lowering his voice, "She is my partner"

"I thought the two of you weren't close."

"She is my partner!" he is pretty sure the sentence is quite self-explanatory so he is not that sure why he has to keep repeating it.

"And she is in love with you."

"She is not! I let myself get captured by terrorists for her; she beats the crap out of big guys for me. We are partners!"

He gets a bunch of raviolis into his mouth and relaxes into the sudden silence, even if it only last for the next ten seconds.

"Are you -" E.J.'s voice is suddenly more serious than pissed "-are you in love with her?"

He is finally so upset by the topic at hand that he doesn't care if she is displeased anymore.

"We. Are. Partners!"

"You keep saying that as if it made some kind of sense but I assure you, Tony, it doesn't. I've had partners, good partners, I wouldn't let myself get captured by terrorist for them. For God's sake I wouldn't let myself get captured by terrorists for you!"

He should have learned by now, to think before talking, to breathe and cool himself before speaking; he really should. It turns out he hasn't.

"I wouldn't let myself get captured by terrorist for you either!"

The dinner is over before the big lady in the operetta has a chance to sing.

Balance, Ziva has learned from a short age, is crucial in life; balance is what keeps you from falling every time you move. Balance, if you master it, makes you a faster runner, a more accurate shooter, a better fighter.

The right balance can make you dance like poetry and jump like a cat.

She works hard for balance; she has a healed scar for every wound, a nightmare overcame for every mission that went wrong, a dear friend found for every family member she has lost.

Somalia's dessert is still tattooed in every inch of her skin but so it is the caring touch of a loved one.

Balance is the key.

She has Tony to help her out to get up every time she falls, to pull her out every time she has given up.

She can live with that.

They are supposedly out to celebrate, both teams are, E.J.'s and Gibb's, although more than a common celebration for having caught a killer, it looks like two different events, coincidental just in place and purpose.

At the Team Gibbs booth, cheer and beer run like Forrest Gump and Ziva leans on him till her lips are mere inches away from his ear. "Shouldn't you go over there?" she says with a quick head movement indicating the place where Team E.J. celebrates.

"Not really," he answers in a low voice barely audible over the music.

"Oh. I see." She takes another drink and leans one more time, "What happened?"

He is tempted to answer that five years ago a sneaky Mossad agent appeared and it all got dramatically complicated after that, instead, he just shrugs his shoulders and says, "Turns out I understood her, but she didn't understood me."

Ziva nods and looks away. At the table, nobody is noticing them, all lost in their own festive spirit and drunk stupor and Tony laughs a little just by looking at them.

Under the table one of Ziva's hands finds his own and gives it a reassuring squeeze, her strong warmth spread all over his side.

Turns out it was this he couldn't live without.