Summary: In the first few days after The Sum in the Parts of the Whole, Cam has a discussion with Booth that gets him to question why Brennan turned him down. The conversation that follows changes everything he thinks he knows about his partner and himself.

~Q~

~ String Theory ~

~Q~

Chapter 1 - Something is Wrong

Dr. Camille Saroyan stood at the base of the forensics platform in the Jeffersonian's Medico-Legal lab and acknowledged sadly that her brightest scientist had visibly grown dimmer in the last few days. Dr. Temperance Brennan looked a little pale, a little reduced, very quiet.

If there was one thing Cam prided herself on, it was her street smarts. She was one of the rare few who managed to combine the abstract experience of medical school and a career as a forensic pathologist with the concrete experience of the school of hard knocks and a former career as a NYPD street cop. She knew plenty of science, but she also knew people, even such enigmatic people as Dr. Brennan. She'd known for days that something was wrong.

Cam also knew that helping this particular scientist was not going to be easy.

Brennan was possibly the most difficult friend Cam had ever managed to add to her considerable roster. The reserved genius had found herself forced into a subordinate position under Cam unexpectedly, and the independent anthropologist did not adapt easily to Cam's demand that everything go through the boss first. Brennan's flashing leaps of insight could not easily be explained to a more concrete thinker like … well, the other 99% of humanity. So rather than explain, Brennan was in the habit of acting on impulse. The previous boss may have allowed that, but Cam put her foot down. They'd clashed, heavily. Cam had threatened to fire her and Brennan had threatened to quit. Only FBI Special Agent Seeley Booth's subtle intervention had staved off that collision and helped Cam see that she ought to try harder to understand Brennan's method, if not Brennan herself.

Cam had known Seeley Booth well over a decade, having been romantically involved with him back in college and during his earliest days in the FBI. Though they had come together and parted twice, it had been on friendly terms both times. Cam trusted Booth's judgment, so if Booth said she'd misjudged Brennan, then she ought to find out why he thought the difficult forensic anthropologist was worth fighting for. There was also the puzzling fact that every one of the scientists who worked with Temperance Brennan was fiercely loyal to her—they'd all threatened to walk out the door behind her if Dr. Brennan lost her job at the Jeffersonian. Loyalty like that demanded an explanation, and Cam determined she would find it.

What Cam had discovered was that the loyalty wasn't very hard to explain after all. It turned out the hard-headed, ridiculously awkward anthropologist had a compassionate heart, uncompromising honesty, unflagging stamina, and ferocious courage. All this after having been stepped on, hurt and abandoned by people her whole life through. Brennan took near killing blows but always managed to get back up and keep fighting for justice—not for herself, but for those who were weaker than she was. Who wouldn't admire Temperance Brennan, when they looked deep enough to see who she really was. So yes, despite herself, Camille Saroyan found herself joining the make-shift Jeffersonian family that surrounded Brennan, a family by choice rather than blood. Their rapport was strained at times, but always tinged with respect. One thing Cam could count on was that Brennan was brilliant and her intentions were always pure, even if her blunt interpersonal approach bordered on maddening most days.

Despite the inauspicious beginning, they'd gradually become friendly, then friends.

Even after they'd declared a truce, to no one's surprise, it hadn't been easy figuring out how to work with Dr. Brennan. One day early on, Cam had insisted that Brennan explain why she wanted to extract the dentin from a victim's molars and run it through both DNA typing and the gas chromatograph. Keeping an eye on the lab's budget was one of Cam's responsibilities, and both tests—unnecessary when they already knew the victim's identity—were too expensive. Explain, Cam had demanded. And then Cam spent the next two hours growing increasingly glassy eyed as Dr. Temperance Brennan explained in agonizing detail all the twists, leaps, turns, backtracks, side trails, rabbit trails, meanderings, musings and hyperspace jumps it took for Brennan to notice that something was 'off' with one of the molars. Yet towards the end of Brennan's dissertation, the explanation had made sense, and Cam had finally relented (partly out of sheer exhaustion). The results had revealed the astonishing fact that the molar did not belong to the female victim, but to a man who'd grown up in the Midwest. The tooth had led straight to the killer.

Amazed, that is what Cam had felt. Just … astounded. Hours after the arrest, she went back to Brennan and asked, "How long did it take you to figure out that tooth was a clue?"

Brennan's brow took on its typical wrinkle as she searched her memory for an answer. "No more than a minute. I could tell just by looking at it that the size and coloration were inconsistent."

Cam nodded. "And how long did it take you to decide which tests to run?"

Again, the puzzled brow. "I … just knew."

"Hmm," Cam said. "But it took you two hours to explain it to me."

"Yes," Brennan confirmed. "You wanted to know why I thought those tests would be appropriate given the seeming tangent, and why the tangent was something worthy of being investigated. There was an extensive foundation of information that you needed in order to put my experience and observation into the proper context."

"So basically, it's like Stephen Hawking trying to explain String Theory to a four year old."

Standing nearby, Dr. Jack Hodgins had snorted at this.

But Brennan had brightened and even looked a little relieved. "Yes, precisely." Then, hesitating, she added, "Not that I think you're four years old, Dr. Saroyan."

Hodgins let go a full-grown snicker then ducked before the daggers from Cam's glare could hit him and draw blood.

Cam sighed, knowing when she was on the losing end of an argument. "Dr. Brennan, in the future, when I ask for an explanation and you know it will take hours to explain, just … tell me 'String Theory.' And I'll get it. Okay?"

"So, 'String Theory' is like a code word?" Brennan asked cautiously.

"Exactly. It will save us both so much time."

"Those terms are acceptable."

To Dr. Brennan's credit, she hadn't used the 'String Theory' code very often—only a handful of times in the last three and a half years. And, yesterday. Thursday.

~Q~

Something had gone wrong since Monday morning. Brennan had left with Agent Booth during the late afternoon to meet with Dr. Lance Sweets, a psychologist at the FBI. Everything was fine when Brennan left, but the following morning revealed the disturbing change. Brennan dragged herself into the lab wearing dispirit like a cloak. As for Booth, long a semi-permanent fixture at the lab, he hadn't turned up at all, and no one had seen him since.

The gossip mills were churning, the betting pool was deep enough to swim in, and Brennan's demeanor had grown increasingly listless over the next few days. Cam could see that Brennan was upset and so she'd asked if anything was wrong. The first few times, she hadn't gotten anything more informative than a curt, "I'm fine."

One thing everyone at the Jeffersonian Medico-Legal Lab knew, was Brennan's preferred method of coping with emotional stress. She threw herself into work and became rigidly analytic. She would not admit to distress of any kind and shunned "talking about it" with almost comic distaste. Even in the best of circumstances, the only people who managed to get any emotional disclosures out of Brennan were Angela and Booth. Since Booth was missing, all evidence pointed to him being part of the problem.

Angela Montenegro, quite simply, was Brennan's best friend. The forensic artist had a knack for finding tiny little cracks in Brennan's armor, usually using a combination of psychology and stealth humor, plus a solid understanding of Brennan's history. In order for anyone to understand Brennan, they had to know her history, and that was something that Angela knew very well indeed. (Though how she had learned it was a puzzle Cam was still trying to unravel.)

Whatever had happened, however, Angela hadn't gotten far with Brennan this time. She'd tried several times to engage the reticent anthropologist in a conversation but found herself gently rebuffed at every turn.

Booth, well, he was something else.

Cam wasn't a romantic by any stretch of the imagination but, if ever she was going to believe in a concept like 'soul mates,' then Booth and Brennan were the exemplars. Special Agent Seeley Booth of the FBI worked with Brennan, taking her with him to crime scenes, into interviews, and generally included her in almost every facet of the murder investigations he was assigned by the FBI. The combination of his instincts and her intellect, his people skills and her analytic skills, proved a potent killer-catching formula. The two had a near-100% case-solving rate. He spent hours with her daily, and understood her in ways that even eluded Angela.

Street smart, intuitive, chivalrous and kind, the powerful man of action had been working with Brennan for over five years now. After a rough start, he'd taken a liking to Brennan because he found her refreshingly quirky, honest, and generous. After learning of her painful past, he'd taken to protecting her from further heartbreak. The relationship between them had grown, transforming from friendship into a love affair of epic, Shakespearean proportions. The entire Jeffersonian and half the FBI watched in rapt fascination as Booth and Brennan worked together, sparred, supported and loved each other, and yet never spoke a word about the obvious adoration they held for one another. If anyone asked—and people did, quite regularly—both partners would insist there was nothing going on between them. They weren't in love. Nothing to see here, folks. Move along.

Oh, but there was something to see. There had been, for years. It was beautiful, the way Brennan's face lit up when Booth entered the room, or the way he seemed to grow a little taller when she laid a heartfelt compliment at his feet. If one of them was hurt or endangered, the other turned into a raging, unstoppable force of nature until all was well with the injured partner. Everyone who knew the pair was just waiting for the day when the partners finally acknowledged what everyone else could plainly see: the two completed each other and were meant to be together.

Cam would have bet the family farm on that, if she'd had a farm. Until Tuesday.

Temperance Brennan had come to work Tuesday morning looking like a shadow of herself. Agent Booth hadn't come in at all. Not Tuesday, not Wednesday, not yesterday, not today. Yesterday, Cam had decided it was time to find out what had happened.

She went to Angela first, knowing the artist would have been poking and prying all week. When Angela reported she'd been unable to get anywhere, Cam had tried a direct approach. She'd gone to Brennan's office herself and found the forensic anthropologist staring blankly at her computer's screen saver.

"Dr. Brennan, is everything okay?"

Brennan blinked, glanced up. "Yes, I'm fine. Why?"

"You seem a little down," Cam observed cautiously.

"Well, yes, I am sitting down while you are standing."

"No, I meant … emotionally."

"Oh." Brennan was very still, eyes unfocused again. "It's nothing," she finally admitted.

Cam pulled a chair closer to Brennan's desk and took a seat. "Did something happen with Booth?"

Brennan was a genius, literally, and miles ahead of everyone else where science or math was concerned. But in matters of the heart, in the vagaries of human emotions, she was generally the opposite of genius. Brennan struggled to understand the most basic nuances of feelings and motivations in others. So she was quite surprised to hear Cam zero in on the source of her woe, when she thought she'd been hiding her distress so well.

"Why do you think it has something to do with Booth," Brennan deflected.

"You're moping and he hasn't been by the lab in three days. It was a reasonable assumption that there's a correlation. Or, perhaps, cause and effect."

"Oh, I see. Yes, you've formulated a reasonable hypothesis from those observations."

Cam smiled a little fondly. Reasonable hypothesis indeed. "So, what happened?"

Brennan seemed to deliberate for a few moments, clearly working out whether to confide or deny whatever was troubling her. Finally, she reached a decision.

"You've known Booth a long time," Brennan said quietly.

"Yes, over 16 years now."

The twisting of her hands in her lap gave away just how unsettled Brennan was. If anything, her face had become even more drawn in the last moments. "Then you know how to make him feel better."

Cam leaned forward, curious and concerned. "Usually you are the one who makes him feel better."

Brennan's silvery eyes sparkled brighter than usual, glazed in tears. "I … I can't. It's my fault."

"What's your fault," Cam asked gently.

"I crushed his heart," she whispered. "Metaphorically speaking."

Confusion was not an emotion that Cam enjoyed feeling. She held back a moment, giving Brennan a pause to regain control and herself a chance to figure out what she should say next. Getting more information seemed like the best approach, at least for now, so she asked again. "What happened?"

"He said he wanted to give us a chance." Brennan was twisting her hands relentlessly now.

"And you said no," Cam inferred.

"Yes. I mean, you are correct. I said no. I had to." Her hands stilled and clenched until the knuckles bled white.

"Why?"

To Cam's amazement, the tears that had been glazing Brennan's eyes now overflowed.

Brennan held Cam's gaze for a moment, but then she dropped her eyes and pressed her face into her hands. The only answer she could manage was "String Theory."

Both women remained silent for a moment. Brennan was pulling her scattered thoughts together and Cam was waiting for her to finish collecting them. When Brennan lifted her head and had recalled her errant tears, Cam decided to ask if String Theory extended to Booth.

"Does Booth know why you said no?"

It was a valid question, and Brennan gave it careful consideration before she answered. "I tried to explain, but I suspect he didn't grasp the nuances of what I was telling him. I was … very emotional. Perhaps I didn't express myself with my usual clarity."

"So, possibly he doesn't understand why you turned him down," Cam restated.

Brennan wasn't completely oblivious to the power of emotions; rather, she was relatively naïve as to the ways other people expressed them. She knew her partner was upset but she wasn't sure what she could do to fix it; she didn't even know where to begin. Brennan traced an idle finger along the edge of her desk, hating the truth but unable to avoid it. She couldn't help Booth, it would have to be someone else, someone who knew him well and cared about him. But Cam wouldn't be able to console Booth if she didn't know at least a little of what had happened.

"It wouldn't matter if he understood it or not. The result is the same. An insect doesn't understand the forces involved in a shoe crushing its carapace and damaging its body to the point of non-functionality. It dies, even in ignorance of the cause, because the damage is too great to overcome. I crushed Booth's heart. Even if he understands why, it won't reverse the damage."

"We're talking about emotions, however, not physical injury. Sometimes, the worst emotional damage is caused by lack of understanding. Sometimes knowing why can help mitigate damage."

Brennan shook her head, the tears flowing again. "He wants a romantic relationship, and I can't…."

Cam tilted her head curiously. "You can't. Does that mean you want to, but can't. Or that you can't because you don't want to."

Her brow knitted in bewilderment. "I don't know what that means."

"If your String Theory weren't an issue, would you want to be romantically involved with Booth?"

There was a very long pause. Cam wasn't sure Brennan was ever going to answer. But finally, the whispered reply reached her and sent Cam's own heart tilting over the edge.

"Yes."

It was the saddest 'yes' she'd ever heard.

~Q~

A note about the title:

I chose the title of String Theory because of both it's extremely complicated underpinnings—you have to be a Ph.D in physics to truly understand it—and because of what it is hoped that theory can do. Superstring Theory is moving us gradually towards a "theory of everything" that will unify the observations and predictions of both General Relativity and Quantum Physics, which without the 'strings' seem to be at odds with each other. Both Relativity and Quantum physics are amazing theories in their own spheres, but put them together and they clash.

Sounds a little like our two favorite crime fighters…. :)

If ever there was a shorthand way of describing how Brennan's mind works and the complicated nature of Booth and Brennan's relationship, String Theory is a contender. The depth of history and conflicting observations between those two can only be reconciled with a fundamental understanding of the forces that propelled them together and then held them apart. Understanding the dynamics between Booth and Brennan requires an extensive education in 'Bonesology.'

Please understand, when I use the word "theory" here, I mean in the scientific sense: a testable model that explains observations and makes verifiable predictions which are further tested and refined. In science, a theory is not a guess or hypothesis; it's not a fact, either. (In science, 'facts' are observations that have repeatedly been confirmed and are generally accepted as reliable and 'true.') A theory uses facts gathered from repeated tests to explain what is happening and that explanation in turn predicts what will happen next. Theories can be disproved by making new observations or finding new facts that dispute them but until that new evidence emerges, the theory holds as a reliable way to explain what is happening and why.

So, I present to you my 'theory' on what happened between Booth and Brennan that resulted in our observation of Brennan saying no and Booth deciding not to fight for her. I have this story completely written and I'm currently fine-tuning the last chapter.

Thank you for reading and I'm really excited to share my ideas with other Bones fans! :)