A/N: So, anyone who has read anything I've written knows that I am particularly inspired by music... and this Christmassy one-shot is no different. The premise for this fic was based on the song The Shadow Proves the Sunshine (hence the title) by Switchfoot, one of my favorite bands. I wouldn't call it a songfic, per se, but it was definitely inspired by the message of the lyrics. I wish I had something more profound and interesting to say here, but since I don't, I'll get on with the disclaimer so you can just read the darn thing.

DISCLAIMER: My ownership is zero. Bones and all related indicia belong to 20th Century Fox, and the song lyrics and title belong to Switchfoot. Absolutely no copyright infringement is intended, it's just for fun!

We are crooked souls tryin' to stay up straight,
Dry eyes in the pouring rain, where
The shadow proves the sunshine
The shadow proves the sunshine

Two scared little runaways
Hold fast to the break of daylight where
The shadow proves the sunshine
The shadow proves the sunshine...

- The Shadow Proves the Sunshine, Switchfoot

Seeley Booth's eyes strained for a glimpse of the outside world, seeking detail in the unformed shapes beyond the darkness. Instead, they came to focus on his own reflection in the glass window; eyebrows drawn together, lips tight, arms crossed. In the background he could see his partner curled up in an airport lounge chair, arms wrapped around her knees, nodding off. He almost smiled; something about the way her chin would slowly drop towards her chest, eyes fighting to stay open, then suddenly her head would jerk up and she would quickly gaze around to see if anything had changed. To see if she had been asleep without even knowing it.

Then he remembered where he was, and why, and what tomorrow would be, and the fleeting happiness was sucked out of his chest. Outside of the airport, ice coated the runway, weighing down the jets' wings and freezing the engine motors in place. He left the window and walked to the center aisle, peering up at the massive schedule board. According to Chicago's O'Hare International Airport, it was nine thirty-nine PM on the 24th of December, and their flight was postponed indefinitely. Crews of workers were doing their best to free the plane's wings and clear the asphalt of slick, dangerous ice, but they could only do so much. They were on all sides battered by a furious winter storm; snow fell faster than it could be shoveled, and the ice would no sooner be broken than mend itself at the cracks.

Why couldn't we have been flown out to Miami? Booth thought to himself, reading the delays on the schedule board. Planes incoming from Florida, California, Texas, Washington, Nevada, and several other states in the Union had been postponed or rerouted, and not by any fault of their own. Booth shut his eyes and thought of sugar-sand beaches in Florida, and groaned. If the slew of corpses they'd identified had been found in a swamp somewhere in the Sunshine State, where flip-flops never retired to the back of the closet and ice only came in drinks, they would already be home. He would be reading Parker T'was the Night Before Christmas like he always did on Christmas Eve, then after the boy had fallen asleep he would quietly wrap the other half of his presents and stash them under the tree. He would scarf down the milk and cookies left in the kitchen for 'Santa' before curling up under his heated quilt and falling asleep, perhaps to the sound of sleet slapping the window panes.

Instead, Parker was with Rebecca and Captain Fantastic, and Booth was stranded in the coldest circle of hell, where the ice never melted and little boys rarely saw their fathers. They had flown out to Illinois two days ago to identify some gruesomely assorted remains, with plans to be back home by the morning of Christmas Eve. Mother Nature disagreed, however, when she sent a massive snowstorm to swallow the city. Ice befell the entire area late the previous night, and twenty-four hours later, still had not stopped. There was a period earlier that morning when the wind and snowfall temporarily abated, and the powers-that-be were hopeful that planes might be hitting the skies by late that evening. Their hopes were buried under a mountain of fresh powder, though, and at this rate did not appear that they would be dug up until sometime late the next afternoon.

Booth yawned, feeling the weight of the past twenty-four hours rest heavily on his shoulders. He had spent what felt like hours arguing with Rebecca on the phone—how he was never around to spend time with Parker, how his job took precedent over his family, how disappointed his son would be not to be able to spend Christmas with his father. He had tried to explain that he had about as much control over the weather as she did, but it did nothing but stoke the flames of her anger. He knew in his heart that she was only upset because Parker was so disappointed, but didn't she realizes he was just as disappointed as his son, if not more so?

Booth scouted out a coffee cart and purchased two cups of the murky ooze—not dissimilar to what one would find in hospital waiting rooms, the dredges left over after the doctors and nurses took the lion's share of the good stuff—and wandered back over to where Brennan was napping lightly in her seat. When he sat down in the seat next to hers her head shot up, eyes fluttering open. Her tense muscles relaxed when she caught sight of him, though, and a tired smile touched her lips.

"Thanks," she said when he handed over her cup. Booth took a sip of his and made a face.

"I wouldn't thank me if I were you," he muttered. She took a sip of the black sludge and made a similar face, swallowing it down forcefully.

"Well, it was a nice gesture," she offered, setting the cup down on the floor next to her chair. He choked down the remainder of his cup in one fell swoop, setting it on the floor next to hers and sighing heavily. They both leaned back into their chairs, watching the snow continue to fall outside of the window.

"It's like being inside of a snowglobe, isn't it?" Brennan finally said, and not without a note of whimsy. Booth looked at her curiously.

"That's kind of poetic for you," he said. She shrugged.

"I am a writer, Booth," she said. "My talents are not relegated to pure scientific inquiry."

"I guess not," he replied, scooting further down in his seat and crossing his ankles in front of him, fingers laced on his abdomen. "If this is a snowglobe, though, someone's been shakin' the hell out of it."

"My dad used to buy me snowglobes whenever he went somewhere," Brennan mused. "You know, the cheap plastic kind with the little figurines inside and the signs that said, 'Welcome to wherever', like New York or Chicago."

"Then there should be a sign outside somewhere that says, 'Welcome to Hell'," Booth said acidly. Brennan frowned, brows knitted with concern.

"I'm sorry you aren't going to be able to spend Christmas with Parker," she offered. "I know how much that upsets you."

"No, you don't," Booth said sourly. "You spend every Christmas in Guatemala or Peru or somewhere hot, looking at dead people. You don't even spend time with your family, you have no idea." He saw the hurt look cast over her and immediately wished he could reel in his words. She looked out at the snow.

"Booth, I spent the last seventeen Christmases alone," she said quietly, shifting her weight in her seat away from him. "Last Christmas was the first time I've ever had anyone to spend it with. It takes some getting used to."

"I'm sorry," he said, and he meant it. "I shouldn't have said that."

"It's fine," she said, still avoiding his gaze. He could see her features cool, the way they did when she took an emotion she was feeling, stuffed it into an envelope, and filed it away. Like a letter in a bottle, tossed into the ocean—it would never be read, never be seen again, unless the broken pieces of glass washed up on a far shore somewhere. "You're just upset."

"I am," he admitted, rubbing his eyes with his thumb and forefinger. "But that's not a good reason to take it out on you. I'm sorry."

"I forgive you," she said, looking over at him with a sad sort of half-smile. "You know, I was going to have Dad, Russ, Amy, and the girls over for Christmas dinner—the whole family. That sounds so strange to say." Booth felt an incredible pang of sadness bite into his gut and twist.

"That's great, Bones," Booth said, remembering their last gathering as a family. "This time your dad could have a tree and everything."

"He had a tree last year, Booth," she corrected. "You made sure he did, that we all did. You made Christmas for us." A flush crept up her neck and cheeks, and Booth smiled down at his lap.

"Trees don't make Christmas, Bones," he said. "Family does. You already had all the Christmas you needed in that conjugal trailer; I didn't bring you guys anything that wasn't already there." Their eyes caught, digging into one another for what lay beneath the surface. Under her eyes he felt like he could see smooth stones, ripples in the bottom of a tide pool; a world under cool grey water. In his, there was an endlessness that was dark but warm, like the center of a flame that does not quite touch the wick.

"You made me stay, though," Brennan said, half an argument and half a statement. "I was going to Peru, to spend Christmas alone. I was going to go look at skeletons. You told me to stay, to make Christmas for my dad and for Russ and the girls. Our family wouldn't have come together at all if it weren't for you. You did give us Christmas, Booth. One way or another, you did." Booth tore his eyes away from hers, turning back to the ice gathering on the windowpanes.

"Yeah, and what did that get you now?" Booth asked bitterly. "Now instead of missing your flight to Africa—"

"South America," Brennan corrected.

"—you're missing time with your family, with the people you love. It's just a whole lot of heartache," he said, his tone miserably defeated. Brennan got the feeling that Booth was projecting his own pain onto her circumstances, but the sentiment still held nonetheless.

"That is true," Brennan said after a minute of quiet contemplation. "I feel much sadder now than I ever have been before at Christmastime, at least in the past decade." Booth looked up at her in mild confusion; was this her way of trying to make him feel better? He knew she could be emotionally challenged sometimes, but even for her this was thick.

"But sadness, like any emotion, is comparative," she continued. "There are no absolutes; it falls on a sliding scale. It's subjective. What is very depressing to some may not be that depressing to others. It cannot be quantified empirically."

"Bones, being away from your family during the holidays is always depressing, no matter who you are," Booth said. She shook her head.

"I don't think you understand what I'm saying," she said.

"Well what's new?" Booth muttered.

"For example," she said, "take the concept of coldness. 'Cold' is a relative term, it is not empirical data. The only definition of cold is that it is not sensibly hot; there is no quantifiable unit of 'coldness'. Fifty degrees Fahrenheit may be cold, but so is negative fifty degrees Fahrenheit."

"Okay," Booth said slowly, not quite following her. She pursed her lips together, trying to think of a way to clarify her thoughts.

"There are three laws of thought, of logic," she explained. "The law of identity, the law of non-contradiction, and the law of the excluded middle."

"Oh Lord, here we go" Booth groaned.

"The law of non-contradiction," Brennan continued, despite his reaction, "states that something can only be what it is, or what it is not. That is, X can only be X, or non-X. A dog can only be a dog, or not a dog."

"Oh-kay," Booth said, nodding his head slightly. "And your point?"

"Well, that only applies to empirical data. Heat and coldness don't follow the law of non-contradiction. While a temperature can only be, say, 50 degrees or not 50 degrees, the concepts of 'hot' and 'cold' can fall anywhere along a spectrum—very hot, sort of hot, lukewarm, tepid, cool, cold, freezing…"

"Right, right, I get it," Booth said. "Squint stuff, it is or it isn't. That's science. The other stuff…"

"It's subjective, based on perception," Brennan said. "It varies by person. The freezing point of water never changes—it's zero degrees Celsius, everywhere, all the time. But the idea of 'cold' varies by person. You might think one temperature is comfortable, while I might think it's freezing. It just depends."

"Right," Booth said. "I still don't follow you. Why does that matter?"

"Because," Brennan said, almost impatiently. "Emotions are the same way. There's no such thing as 'sadness' or 'not sadness'. There's a spectrum of what it is to be sad. You can be extremely depressed, suicidal even. Or you can be just a little sad, something you hardly even notice. You can fall somewhere in the middle, distraught but at the same time realizing it is not the end of the world. It just depends on who you are, and what responses certain situations elicit from you. There is no equation that says, "When X happens, every person will emotionally respond with Y.""

"So…" Booth said, still in the dark.

"So, when a close family member dies, it receives a strong emotional response cross-culturally," she continued. "Every person in every culture responds to death with some level of grief. But to one person, that death may have a more powerful impact than to another. If you have never experienced the death of a loved one before, that person's death is a very traumatic experience. If, on the other hand, you have had dozens of family members die, it will probably not impact you as severely."

"Nobody died, Bones," Booth said, puzzled. "What does that have to do with anything?"

"Booth," Brennan said forcefully, as if she were trying to grab hold of his utmost attention and comprehension in order to make a very important point. "I don't know how to explain this properly, because I don't… I don't talk about my emotions very often. It is difficult for me to do. But when you made me have Christmas with my family, when you made me reconnect with my father and Russ… it changed the way I experience pain." Booth did not know how to respond to this statement, and instead allowed her to briefly collect herself and continue.

"Before, when I spent Christmas alone, in Peru or Guatemala or Afghanistan, it didn't bother me. At least, I didn't think it did. I was so comfortable with spending time alone, time that was supposed to be spent with others, that being alone did not elicit a strong emotional response from me. Those first few years, after my parents and Russ left me… they were different. But after so long, I was numb to it. I didn't feel it anymore.

"But then my father came back, Russ came back, and for the first time in almost twenty years we spent Christmas together. We decorated the conjugal trailer and exchanged gifts and got to see the lights on the tree and for the first time in a long, long time, I got to have a family. I got to know what it was to spend Christmas with people you love. That changed me, Booth. All these years, I hadn't known I was sad until I felt what it was to be happy. I didn't know what it was to be lonely until I wasn't alone anymore."

"The world didn't know darkness until God made the light," Booth said, focused with rapt attention on Brennan's expression. It was soft, almost vulnerable, but somehow passionate. It was then he realized—it was one of the very few times he ever saw her speak purely from the heart. No science. No data. Just heart.

"I didn't know I was sad, Booth, until you helped me reconnect with my family. Until you helped me be happy," Brennan repeated, her eyes rimmed pink. She blinked back the moisture that had collected in the corners, looking away briefly. "So yes, I am more upset this year than in years before that I am spending Christmas without my family, and it is because of you, but it is only because I know what it is to be with them now, to enjoy their company. Like you said… knowing the light proved that there was darkness to begin with."

"The shadow proves the sunshine," Booth said, swallowing back the bulge that had formed in his throat and reaching out physically to Brennan, enclosing her hand in his. A current rippled between their skin, like an electric pulse. Whatever coldness there was beyond them, they did not know.

"Yes," Brennan said, looking down at their touching hands. She slid her fingers in between his, intertwining them and solidifying the connection. "The shadow proves the sunshine."

A/N: Sooo, what do you think? I tried not to make it too fluffy as to be unbelievable, but still kind of holiday heartwarming. Was it good, bad, ugly? I love reviews, so leave me one and let me know. :) Thanks!