Author's note: All the usual disclaimers apply – I don't own the show or the characters, only the words on this page. This follows on directly at the end of 'Counterfeit reality'. As always, I'd love to hear what you think.

Balanced equation
by BHP

Kim Hall: You and your brother are a lot alike.
Charlie Eppes: You think so? Most people can't get over how different we are.
Kim Hall: Well, yeah. The interests are pretty different, but the approach: this one part exuberance, two parts obsession, that's pretty much identical.
Numb3rs, season 1, 'Counterfeit reality'

"I'm sorry." Charlie's voice was quiet, just clear enough to be heard over the rolling credits on the television screen. He couldn't look at Don, finding the apology easier that way. But he heard material rustle as Don moved to find the television remote and mute the sound.

"What for?" Don sounded puzzled. Charlie couldn't wrap his mind around the idea that Don never seemed to think an apology was necessary. No matter what Charlie did, or said, or didn't do.

"The box." Charlie looked at the opened cardboard container, filled with memories of Don's life before. Before Don came back to Los Angeles, before their mother died. Just … before.

"Dad told me not to open it. Asked me if I really thought I should." Charlie could feel the weight of Don's gaze on him, shadowed by the dim light of the room. Yet he felt no judgment in that dark gaze. He shifted uncomfortably in the chair, running his hands along the arms. Working up the courage to say what was needed.

"So, why did you?" Curiosity filled the question, but not one ounce of anger.

"Kim thinks we're a lot alike, you know." Charlie mused, knowing the tangent would irritate his brother, but unable to stop himself. He'd thought he was ready to talk about this when he'd left home, and all through the cab ride to Don's apartment, but reality had a funny way of making him think twice. "Do you think she's right?"

"Same parents, dark hair, brown eyes, similar heights." Don sounded faintly amused. "Physically, sure. The rest of it? I don't know. Never thought about it, really." Don stretched out a hand towards the box, reached in and pulled out one of the photographs. Charlie could see enough in the dim light to make out two people, Don's arms around Kim, both smiling happily. "What's your take on it?"

"Well, I'd never actually given it much thought before, either." Charlie wasn't quite sure what to say, put on the spot by Don in that way only an older brother could manage. "So I gave it some thought now."

He shifted in the chair again, and dug a hand into the back pocket of his jeans to pull out a few battered sheets of paper. He opened them up, pressing the creases flat on the table and using Don's empty beer bottle to hold them still. He looked up and caught the incredulous amusement in Don's eyes.

"You made an equation? Of us?"

"Well, I tried." Charlie's sheepish admission was followed by chuckles from both brothers. "But I haven't been successful yet. I'm working with words, not numbers, for starters. And then I need to find some value that equals what we have, what we really are, as opposed to just the bits that Kim sees. That's the biggest problem. Do you know just how hard it is to get a handle on you?"

The stunned look of shock on Don's face was worth that admission. Charlie thought that perhaps he should make it clear, more often than he did, just how much he thought about Don, about who his brother was, rather than what Don did for a living. And just how little he was sure of, given how Don was such a self-controlled person.

"Charlie, there's nothing difficult there. I'm just a guy. You know, nothing special, just average." Charlie wondered at the acceptance in Don's voice, the lack of bitterness at seeing himself as completely average and in the permanent shadow of a brilliant younger brother.

"Now, see, that's where you're wrong." Charlie was intent on his sheet of paper, pointing out the things he'd listed. "The average guy just goes along, mainly does the minimum necessary to get by, and lets the world just go on around him. You're definitely not that guy." Charlie glanced up and was momentarily side-tracked by the odd, wondering look on Don's face. Charlie had slipped automatically into his teaching tone, forgetting that it gave him a level of objectivity that allowed him to say things he'd otherwise stumble over.

"For you, I've had to factor in a bunch of other things, starting with duty, courage, intelligence, loyalty, and the rest of these …" Charlie's finger ran down the page, along an impressively long list of words. "The problem is that I keep coming up with new things that relate to other things on the list, and then I've got to go back and revise from the beginning. You're absolute murder on an iterative process, Don."

00-01-11-10-00

Don couldn't contain his laughter at Charlie's disgusted tone. But under the laughter, he felt close to tears. All these years apart, trying to be his own person – and all that time, Charlie had been thinking of him in such glowing terms? Looking on him as an example, someone to emulate. How had he managed to be so blessed as to have a brother who only saw his virtues? Who maybe even saw his faults as virtues? He suddenly remembered what his dad has said to him a few weeks earlier, after the series of staged train accidents. He'd laughed at the time, but right now he was willing to admit that maybe Charlie was still trying to impress his big brother – by trying to understand and be like Don.

That was a sobering thought. Did he really want Charlie to end up like him? Obsessed with work, wholly committed to his job without any thought of a life outside of it, spending his nights alone? Afraid to make a life with someone special again, because he'd had that once and lost it? Don wanted more than that for Charlie.

"Some list you've got there, buddy." Don tried to get a closer look at it, but the flickering light from the television screen hid more than it made clear. Still, it was a long list. "So, where's the list for you?"

He only saw the slight flinch because he was looking right at Charlie, then he looked at the crumpled papers to see Charlie tap one long finger over a much shorter list on a second sheet.

"Well, there's intelligence, and family, friendship. Then there's stubborn, and obsessive …"

"What about loyalty, Charlie? And duty and courage as well?" Don couldn't believe that Charlie didn't see those things in himself, but the look of surprise on his brother's face was a give-away.

"I'm not all those things, Don. I'm just a math geek."

"Hardly. You've got the guts to consult to the FBI and the NSA, and whoever else I don't know about yet. So, courage and duty."

"That's just math, numbers. That doesn't take courage."

"Sure it does. All those people who don't know you, who don't want to listen to you or hear what you saying. Yet you keep at it until they get it. Because you want to help, because you can make a difference. That's not an easy thing to do."

"You really think so?"

"I do." Don shook his head, somehow not surprised that Charlie could underestimate himself so badly. In the academic world, Charlie was supremely confident and aware of his worth, but he doubted himself fiercely outside of his chosen field. "I know I'm nowhere near as smart as you, Charlie, but on this, I know I'm right."

"You're a different kind of smart, Don. All sensible, practical, useful. The sort of smart that gets things done, makes things better." And there it was again, that hero worship that their father kept pointing out. Don was absurdly pleased at the way that Charlie looked up to him, especially after spending his childhood believing that he could never measure up to his little brother.

"So, you'd better add those two to your list for you." Don leaned forward and tapped the page. "Then you'd better add loyalty." He settled Charlie's stillborn objection with a silent glare. "If I need you, you're there. That's more than good enough for me."

Charlie's smile, shy and pleased, made Don think that maybe it was time he said these things more often. Time he talked to his brother about all the things that really mattered, outside of the time they spent together on cases. Perhaps it was even time to let his brother back into his life, more deeply than he'd wanted to believe he could.

"Just curious here. What did Kim think we have in common?" Don really wanted to know, but Charlie's silence dragged the suspense out. "Charlie?"

"Well, she said …" Charlie swallowed and glanced away for a second. "She said that it's how we approach things: one part exuberance and two parts obsession."

Don laughed out loud at that. He fell back on the couch and stared at the ceiling for a few moments before looking across at his brilliant baby brother. "You know, she may just be on to something with that."

00-01-11-10-00

Charlie was surprised at how well Don seemed to be taking Kim's words. Calling someone obsessive was insulting: he should know, as it was a favourite insult from many children when he was still at school. He'd always known that he tended to obsess about things, especially numbers, so he'd learned to let the insult slide off him. But to hear someone say the same thing about Don made him angry.

"How can you laugh at that?" Charlie's question ended Don's laughter.

"It's funny, Charlie."

"What? It's funny that she insults you like that?" Charlie really didn't understand Don sometimes.

"But it's not an insult to you?" Don's question was quiet. Charlie was reminded suddenly that his brother was a seasoned FBI agent, with an insight into people that rivalled Charlie's insight into numbers. An expert in interrogation techniques that had suspects confessing before they even realised what they were saying.

"For me, it's true." Charlie shrugged the words out, not sure why Don seemed saddened by the admission. Then his brother smiled at him, sharing a confidence.

"Well, it's true for me too." Charlie was shaking his head in denial, but Don went on. "She always did seem to know me better than I knew myself."

Don picked up the discarded photograph on the table and leaned over to hand it to Charlie. He rested an elbow on his knee to stay leaning towards his brother, and pointed at the image. "We look happy, don't we?"

Charlie nodded, taking the time to really look at the photograph now that he had Don's permission.

"But even then, I knew she wanted more from me. More time, more ambition, more attention … just more of me, I guess you'd say." Don sighed and flopped back on the couch, while Charlie found himself leaning forward in his chair, desperate not to miss this vital insight into his always-composed older brother. "We put it down to both of us building our careers, to particularly bad cases, or just to the heat or office politics. But somewhere, inside, I guess I always knew."

Don's voice trailed off, and Charlie waited. Then waited some more. Listened to the distant sound of sirens and wondered, briefly, who'd run foul of the LAPD at this time of the morning. He waited until he couldn't find the patience any more. "Don? What did you know?"

"That there were people in the world that I would give up anything for, but she wasn't one of them."

Charlie could hear the loss so keenly, he moved without thinking. Dropped the photograph back in the box, and settled himself on the couch to the left of Don. "How can you be so sure?"

"Because when Dad called, about Mom." Don tipped his head towards Charlie, gaze inward, not noticing how Charlie tipped his head towards Don like a mirror image. "When Dad called, nothing mattered except coming back home." Don blinked and looked at Charlie. "And that hurt Kim, to see what I hadn't been able to do for her, come so easily for someone else."

"But, it was your family, Don."

"Yeah. She got that. But by then, so was she. I chose family I hardly saw or spoke to, over the person I shared a home with. Over the woman I loved." A slightly hitched breath was the only clue Charlie had about how hard it had been for Don to make that admission out loud. To tell someone, anyone, something so personal.

"It's not a crime, you know."

"But it is a failure. In me. In my approach to life." Don's self-recrimination was clear.

"Maybe in her approach too, Don." Charlie had found the start of something promising, and intended to follow the thread through to its end. "If you were family to each other, we'd have seen her that way too."

"Really? When you'd never even heard her name?"

"That doesn't matter." Charlie knew Don needed to hear this, as much as he needed to say it. "If she was your choice, then yes. You mean that much to us – to me – and she could have too. She would have. All she had to do was come with you."

Charlie's certainty brought Don's gaze up to meet his, and for once in his life, Charlie felt that he had just done something heroic. Something that made him equal to his brother. Maybe love could do that.

00-01-11-10-00

The simple acceptance and forgiveness in Charlie's statement almost broke Don's composure. Charlie always seemed to expect so little, yet offer so much to everyone else.

"You're a better man than I am, Charlie." At least he could be honest about his failings.

"I'm not following."

"It's that easy for you to just let this go? Ignore the fact that you should have known about this? That I should have been the one to tell you?" Don's voice had grown louder with each question, but Charlie didn't react. Then he blinked slowly, a look Don had come to recognise as Charlie's way of marking a solution to a problem.

"You're my brother. And as you pointed out, I didn't tell you anything about my life three years ago, either." Charlie shook his head sadly. "Besides, I'm equally to blame. You're not the only one who seemed to forget how to use the telephone." Charlie's sudden grin was unexpected and mischievous. "Maybe that should go on the list of things we have in common."

Don's laugh was short, strangled by the sudden lump in his throat. When had Charlie got so good at reading him? He turned his head to look at Charlie, and found himself the subject of careful observation.

"Along with hard-headed, blind to the obvious, and selectively deaf." Charlie snickered at Don's words, and Don slung an arm around his shoulders, pulling him in close for just a second. "Don't tell me Dad wouldn't put all of those on the list in a heartbeat."

Charlie tipped his head to one side, considering, then nodded sheepishly. "Probably."

Don sat quietly for a moment, wondering at the sudden closeness he felt to Charlie. A sense of finally being in the right place, at the right time, and being witness to an unexpected miracle. The rebirth of a relationship that was so much more important than he'd realised when he'd joined the FBI. A relationship that had become vital to his happiness and sanity. And all packaged in one hyperactive, curly-haired genius. Who was looking decidedly guilty.

"What gives, Charlie?"

"What do you mean?"

"What are you feeling guilty about?"

"How do you do that? Oh, never mind." Charlie ducked his head. "I shouldn't have opened the box."

"Oh." Don suddenly realised that although Charlie had already apologised for the infringement, he'd never answered Don's question about his reasons. "So why did you?"

Charlie sat silent for a few minutes, fingers automatically moving to turn over a piece of non-existent chalk before falling still.

"I didn't expect this." Diffidence filled the words.

"This?" Don was having trouble tracking Charlie's thought processes. Not a new situation, by any stretch of the imagination, but unexpected now.

"This evening. This talk." Charlie looked up and quickly ducked his head again. "I didn't think you'd be willing to, I don't know – talk, let me in. So I did some research of my own."

"Research? That's what you call going through my stuff, reading my letters?" Don actually wished he had the energy to be really angry with Charlie for the invasion, but somehow he couldn't do it.

"No!" The horror in Charlie's voice was real. "I looked at the stuff, sure, at the photographs and the framed things – how come I don't know about those awards, by the way? Does Dad even know?" Charlie paused, then dismissed the questions, hand waving in a manner that suggested the subject would be discussed again at some point, probably at length. Don wasn't looking forward to that conversation: those awards were for the sort of things he deliberately kept from Charlie and his father. "But I didn't read anything. I wasn't even sure you'd been engaged until I saw that ring earlier. I thought so, but I wasn't sure."

"Sorry." Don felt the flush heat his cheeks, and hoped the light was dim enough to hide it. Then he thought about what Charlie had just said. "What do you mean, you weren't sure I was engaged?"

"Well, you never said. And I didn't read your letters." Charlie repeated himself, then moved into lecture mode, ready to prove his conclusion. "But you told me that you and Kim were serious. She told me that you'd lived together. You've admitted you loved her." Don nodded at each point. "And I know you. When you commit, there's no half measures. It's all, or nothing. So I figured you were most likely engaged. The probability's actually above the ninetieth percentile."

Charlie's expression was so endearing that Don couldn't help but smile back at him. His little brother was still the same, still always so sure of his logic and conclusions. But he'd grown up a lot along the way, in the years he and Don had spent apart. He'd learned to temper his enthusiasm and certainty with a little more caution and empathy.

"You figured right, buddy." Don reached out to ruffle Charlie's hair, laughing as his brother ducked his head and batted Don's hand away. "And thanks. For not reading that letter."

It had been bad enough reading it himself, but to think that Charlie had read it, had seen Kim lay bare Don's failings: that would have been too much to bear. He could still remember most lines without reading them. He could see them again now, laid out in Kim's careful writing:

It's not that I don't love, you, Don. You know I do. That line had really hurt.

I understand that you need to be where you are right now. She'd understood, but she couldn't, or wouldn't, accommodate his need.

I know you're willing to let your career suffer for being where you feel you're needed. Remember the promises we made each other? I know why you can't keep them, but I can't let them go. This wasn't part of our plans. It's not going to be part of my plans.

Don still had his pride, and he'd prefer that Charlie keep at least some of his illusions about his big brother intact.

"I told you, I've learned a lot from you." Charlie's voice was quiet, but the certainty was clear. "One of those things is that you do the best you can, but sometimes that's just not enough. But you keep going anyway." The admiration in Charlie's glance made Don look away.

"Don't." Charlie's hand on his arm made Don look at Charlie again. "Don't look away. Something else you've taught me is that we're not responsible for other people's decisions and actions." Charlie rested his hand gently over the fading bullet scar on Don's left arm. "My equations led you to the Charm School Boys, but I'm not responsible for this. They are."

"Finally," Don smiled, "you get it. That's what I was trying to tell you at the time. You didn't need to go back to your P vs. NP thing."

"Yeah, well," Charlie hesitated, then went on, "you should listen to yourself occasionally. Don narrowed his eyes at that. "You're not responsible for Kim's decisions. She chose to send back the ring. I know you didn't break it off."

"How do you know that?" It was true, but Don knew he'd never said as much to anyone.

"Like I said, I know you."

There was that faith again, that belief that Don was always such a good person. It was humbling, and somehow also comforting. Knowing that someone would take his side, without a second thought. He'd always known that his dad would support him, no matter his personal views about Federal agents, but he'd never been quite as sure about where he stood with Charlie. They'd always been so different. In spite of that, he knew he'd always take Charlie's side against the world. Now he knew that Charlie would do the same for him.

00-01-11-10-00

Charlie knew he'd never been very good at understanding people. He'd learned at an early age that he was different, and that most people his own age had considered him to be some sort of oddity. Although that was putting it politely; mostly they'd just called him a freak. In the face of fairly constant hostility and derision, he'd given up on trying to make friends. Don, on the other hand, had always been popular and well-liked. It had never occurred to Charlie that what he'd seen might not have been the whole truth. Or that friends wouldn't necessarily go to bat for you. The frank astonishment on Don's face at the moment made Charlie wonder just how many times Don had been let down by people he'd trusted. But that was a conversation for another day.

"You wouldn't end a relationship you cared about without doing everything you could to save it first." It saddened him to even think it, but Charlie knew he had a killer proof for that theory. "Look at us. Three years ago we were barely talking to each other, and just look at us now." Charlie waved a hand around, indicating their current situation. Don's snort of laughter made him chuckle. "Okay, so not the sitting in the dark part, so much as the dinners, the afternoons together, talking about everything and nothing."

"Bet you never thought you'd hear me say I could talk about nothing." Charlie shook his head.

"Not true. I always knew you had it in you, Charlie. It just needed a little help getting out."

"Well, here's something else I bet you never thought you'd hear out loud either." Charlie took a deep breath. "I love you. I know that's no replacement for what you lost …"

"No, it's not." Charlie felt something fragile inside him shrivel and die at Don's agreement. Then Don's hand was on his, warm and gentle. "It's better. You don't care what mistakes I make, or whether I get it right, or anything else. That's more precious than anything I've lost." Charlie saw Don's bright smile, and smiled back as warmth of Don's words filled him. But Don wasn't finished. "I love you, too. Just the same."

"Ah, well, you know." Sudden emotion swamped Charlie and he could feel his composure slipping. "It's late, I should be going." He reached out to gather his lists, but Don's words stopped him. "Stay the night, Charlie. What's left of it. I've got the room."

The open love in Don's voice was impossible to resist. Minutes later, Charlie was settled on the couch with pillows and a blanket, drifting to sleep. Sure at last of his place in Don's world.

00-01-11-10-00

In spite of how late he'd finally fallen asleep, Don was awake just before the clock struck eight. He'd told his team to take it easy today, to make up for the late night raid on the counterfeiters. He didn't expect anyone in the office before noon, which meant he'd be sure to be there an hour before that. Although it was just mainly mopping up left to do. He'd made a good start on all the necessary reports after Kim had left the FBI building last night, burying his memories and regrets in paperwork.

He took his time with his morning routine, but half an hour later he was in the kitchen making coffee. The right way, with freshly ground beans, a new filter, the whole process. Waiting for the coffee to drip through, he stared out the window, just watching. Watching the cars on the street, people walking past, and a plane heading out from LAX. All the time, his talk with Charlie ran through his mind. He'd learned things he'd never expected, and found that he shared a lot more with his brother than he'd ever dreamed. Maybe he should thank Kim for pointing out how much alike they were.

Don poured two mugs of coffee and headed towards the couch. A Charlie-sized lump of blanket, topped with a riot of dark curls, snuffled slightly into a pillow. His brother always had been able to sleep through anything. Don carefully placed the two mugs on the table, and picked up Charlie's scribbled lists from the table. Bypassing the lists of characteristics, Don stopped at the final line, reading Charlie's scrawl: One part exuberance + two parts obsession = ?

Don stared at the page for a few more moments, and smiled gently. This was easy. He pulled a pen from under the magazines on the table, and scored out the question marks. He wrote three short words, and then folded the papers to hide the answer. He slid the papers into his back pocket, reminding himself to give them back to Charlie later. He sat for a few minutes, drinking his coffee and watching Charlie sleep. It wasn't something he'd had the opportunity to do since he and Charlie had gone their separate ways, but it still felt familiar and comfortable. He'd watched Charlie sleep when they were still children, promising himself that he'd always be there for his little brother. He'd slipped up in that department for a while, he knew, but he felt like he was back on track now. He contemplated the lump of blanket for another moment, then reached out to poke at what he hoped was Charlie's shoulder.

"Charlie."

"No. Sleeping."

"Charlie. Come on, sleepyhead. Up and at 'em." Don's good humour grew in proportion to the level of Charlie's disgruntled, almost inaudible, muttering. The noise suddenly stopped, then Charlie's head shot out from under the blanket.

"Don. Morning." Don could see the memories come online, the massive supercomputer that was Charlie's brain snapping into action at unimaginable speed. A momentary flush and a dip of his eyes were Charlie's only concession to their talk, and Don couldn't help but grin. Apparently, the Eppes men could only talk about their feelings at ridiculous hours of the morning and in the absence of sunlight.

"Morning. Drink your coffee while it's hot." Charlie's hand automatically reached out, showing how well the big brother tone still worked.

"Oh. Nice." Charlie's appreciative murmur was clear. "Why doesn't the coffee at your office ever taste this good?"

"Cause if I make it once, I'll be stuck doing it all the time. That's not happening." Don was definite. "Besides, they don't deserve it. You do." Don headed back to the kitchen with his nearly empty mug, relishing the floundering, speechless expression on Charlie's face. He called back over his shoulder, "What time have you got to be at CalSci today?"

"Eleven. Office hours, then a lecture at two."

"Want me to drop you off at home first?"

"Thanks. If you're sure."

"Wouldn't offer if I wasn't."

"Okay." Charlie drank more of his coffee, and added, "I've got bagels at home."

"Yeah?"

"Okay, so Dad's got bagels at home. But stay for breakfast anyway?"

"Sure."

00-01-11-10-00

A while later, Charlie walked slowly from the back door of the house towards the driveway and Don's waiting Suburban. He and Don had taken their time sharing their breakfast of bagels. Plain, with cream cheese for Don, but toasted in his case, with peanut butter. He knew Don thought that particular combination was the ruination of a perfectly good bagel, but he would always smile and tell Charlie that it was fine as long as he didn't expect Don to eat it as well. Now he matched Don's leisurely pace through the garden. It was good to see his brother so relaxed for a change. He knew it wouldn't last – another case would land on Don's desk – but for now he could enjoy watching Don appreciate the little things in life: the scent of the blooming flowers, warm sunshine, bagels for breakfast. Charlie kept dwelling on everything they'd talked about the night before, considering all the angles. It was like an equation he couldn't get out of his head until it was solved, and he had a feeling that this one was going to be harder to crack than the Millennium Problems. After all, those were only math, and in the end, all math was logical. This problem was … something else. Life, maybe, or more accurately, his and Don's life as brothers. Was it really something that needed to be solved, or should he just let it go? Experience it as it came, and not worry about what it all meant?

"You're quiet. Even for you." Don's voice was mild.

"Just thinking."

"For a change." Don laughed quietly.

"Maybe every equation doesn't need to have a solution." Charlie hated the uncertainty he could hear in his own voice.

"You still thinking about what Kim said, and last night?"

"Aren't you?"

"Yeah, but I can live with uncertainty." Don's smile was wide and happy as he looked at Charlie. "Not that there's much of that in what I can see."

Charlie ducked his head awkwardly as he caught Don's meaning, then looked up to meet Don's gaze.

"Maybe not."

"I'd better go." Don patted Charlie on the shoulder and turned towards the Suburban. "See you later?"

"Any time, Don." Charlie was already looking forward to it.

Don already had the keys in the ignition when he reached into his back pocket to pull out Charlie's papers. He handed them to Charlie, the hopped into the car and settled himself in the driver's seat. He started the engine and moved off slowly, calling out through the open window. "By the way, I solved your equation this morning."

Charlie watched until Don was out of sight down the street, waving distractedly with one hand, the other clutching the papers tightly. The curiosity was too much, and he unfolded the creased sheets of paper as he stood on the sidewalk. How had Don found an answer when he couldn't? What had he been missing? Charlie scanned down the page to the final line, to see his three question marks had been scored out and replaced with three words in Don's distinctive hand. He smiled as he read the completed equation:

One part exuberance + two parts obsession = Three parts love.