In a Mirror, Darkly

by Valerie Vancollie

valeriev84 at hotmail dot com

Characters: Charlie, Don

Rating: 15

Summary: There was a certain irony to the situation, that the brother who was a federal agent had been abducted to be used as leverage against the brother who was an applied mathematics professor at a highly respected college. Don Whump, Charlie Angst!

Spoilers: Uncertainty Principle, Vector, Man Hunt, Dark Matter, Finders Keepers, Breaking Point, Black Swan, When Worlds Collide, The Decoy Effect, The Fifth Man, Greatest Hits, Angels and Devils

Note: The first three chapters of this story were written for the Charlie round at Numb3rs Write-Off. I was a member of Team Angst and chose the word prompt decision.

Part I: Charlie: NSA

Chapter 1:

Thursday, 11:27
Dr. Charles Eppes' Office, CalSci

Charlie was just compiling the last of his final grades for his Intro to Calculus class when there was a knock on his door.

"Come in," Charlie called out, looking up and wondering who it could be.

All of the students had gone home for summer already, Larry had gone to visit Megan and his fiance had gone to India to visit her parents. Undoubtedly to start planning the wedding, a thought that still sent a mixture of delight and fear coursing through him. Which left only Millie, his brother and the members of his brother's team and they always just knocked and entered, they didn't wait to be given permission, so he was at a loss as to who his visitor might be.

"Dr. Eppes," a tall blond man said as he entered the room, his suit all but screaming federal agent even if there hadn't been a gun at his belt.

"Agent Banner," Charlie greeted as he got to his feet.

Despite not having seen the man for years, he recognized him instantly as Banner hadn't changed much. There seemed to be a few more wrinkles on his face and some more gray streaks in his hair, but otherwise he looked exactly the way he had when Charlie had first met him in DC years ago. The memories brought a half smile to his face. While they had started off on the wrong foot, the agent scoffing at bringing in a mathematics professor to consult, let alone one so very young, he'd quickly changed his mind. By the end of that first consulting gig, Banner had already been more than willing to listen to what Charlie had to say. For the subsequent two cases he'd consulted on, Banner had been all ears, eager to learn what other ways math could be applied to real world scenarios.

On some level, Charlie wished he knew exactly what it was about the work he'd done that had so thoroughly converted the man as he'd love to be able to use it on other people. Alas, he'd been unable to figure it out, in large part due to the fact that whenever he consulted for the NSA, he never got all of the data. Unlike the FBI, the NSA kept him in the dark as regards to the bigger picture or the overall case. He was sure that he'd be able to do a better and more efficient job for them if he had all of the facts, but that was simply not how the Agency worked and he knew better than to try and push them on the matter.

"How are you?" Charlie inquired. "And did you get transferred?"

"Not exactly," Agent Jeremy Banner replied, approaching the desk. "But I'm in charge of a case that's moved here, so I've followed it across the country."

"I assume this case is what brings you to my office?"

"Yes, though I must admit, your office is a lot nicer than I imagined it would be. And a lot tidier."

"That's because I've only just moved into it," Charlie admitted, knowing the man had already seen how messy his workspace could get when he was in the middle of a problem.

"Still, maybe I chose the wrong profession."

"It's never too late to change."

"Oh, for me I definitely think it is," Banner laughed. "I'm far too set in my ways to alter them now."

"You'd be surprised," Charlie argued. "Some of my students are a lot older than you. Even my father has started taking classes here, though in the Engineering department."

"What? Not in math?"


"Can't win them all," Banner stated before his face turned serious. "So, I guess the first question is, do you have time to consult for the NSA?"

"It would depend on the scope of the project," Charlie answered truthfully.

Although he'd struggled recently to meet all of the demands made on his time, he didn't want to say no immediately. Even beyond Agent Banner's interest in the math, the NSA generally provided him with very interesting problems and his work for them had often triggered lines of thought that he'd gone back to later on and developed further on his own and even published on. With classes over and both Amita and Larry gone, he also had a lot more free time on his hands than normal just now.

"Well, it's something you can work on here if you keep the office secure," Banner began, glancing about. "There's no need to confine you to an NSA office as we've sometimes done in the past."

"That's good, 'cause then I'd have to decline as I can't afford to do that at present."

"Good, now what I'm about to tell you is top secret, classified."

"I am well aware of the security issues consulting for you involves, Jeremy," Charlie replied a little wearily.

It was always the same song and dance, though he supposed it was necessary.

"I just want there to be no misunderstanding," Banner explained, watching him closely. "You are to tell no one any specifics of what you are working on. In fact, you are not to tell anyone that you are currently consulting for the NSA, not even Agent Eppes or anyone else at the FBI, do you understand?"

Charlie sighed, thankful he wasn't currently working on a case for Don like he had been the last time the NSA had come asking for his help. "Yes, I understand."

"Good, now, if you accept this, I shall be your sole point of contact for this consultation, just to make it easier to ensure security. If anyone else from the NSA comes by, you are not to tell them anything either."

"What? Why?" Charlie demanded, slightly alarmed. "Is something wrong?"

"We're not sure," Banner started slowly, suddenly looking weary. "Some information has surfaced that makes us worry that there might be a leak, either in the NSA or with one of the organizations working closely with us and we want to make sure that what we are currently working on remains a secret while another team tracks down the source of the leak."

"Oh, I see."

"Therefore it is vitally important that we have a consultant working on this which we trust implicitly not to be involved."

"I find it hard to see how I fit in that category after all that's happened," Charlie stated darkly, still angry at what had happened regarding Sanjrani and his work.

"The Pakistani issue aside, you have a spotless record and you weren't consulting for the Agency at the time of some of the leaks, which puts you in the clear," Banner explained before an ironic smile crossed his lips. "Besides, Assistant Director Thompkins still speaks quite highly of you."

Charlie relaxed a bit at that. It was something he'd wondered about since the whole security issue fiasco; what Bob thought of it all. He hadn't heard from the man and he hadn't quite worked up the nerve to call him and see where they stood. He'd silently hoped that the Assistant Director had had a hand in him regaining his clearance despite McGowan's clear dislike of everything he uncovered in his investigation. Therefore, it was very good to get confirmation of the fact that he was still in the man's good graces.

"So, what is it you need me to do for you this time?" Charlie inquired, his curiosity getting the better of him.

"Well, see, we've managed to get our hands on a computer that contains information vital to national security," Banner began, placing his briefcase on the desk, opening it and extracting several thick folders. "The problem is that all of the information on it is not only encrypted, but also protected by a highly complex security system."

"I assume that this computer doesn't belong to the NSA?" Charlie asked and then looked up from the first folder when his question was met with silence. Banner's face was grave and gave nothing away. "Sorry, I don't mean to pry, I was merely asking as the origins of the computer might provide some insight into the type of security measures used."

"That information is classified and need to know."

"Well, I do, need to know that is."

"Unfortunately, my superiors do not agree with that assessment."

"Look, Jeremy, I can't help you if you're going to bind my hands," Charlie argued, having forgotten how damned frustrating it was not to simply be given all of the relevant information or to easily be able to obtain it.

"I'll see what I can do, but in the meantime you'll have to make do with what they have authorized you to see."

"Okay, so, what else can you tell me?"

"The information the computer contains may help us uncover the identity of the mole, or moles, currently leaking information on the Agency and its projects."

"So, pretty urgent then."

"That's one way of putting it," Banner agreed wryly. "The problem is compounded by the fact that our internal people don't seem to be making much headway on their own. Do you think you'll be able to help?"

"Hmm," Charlie responded, almost completely absorbed in the figures and algorithms listed in the files.

Quickly, he flipped through them, getting a feel for the complexity of the math involved and how difficult it might be to come up with a way around it. Oh, that was interesting, he didn't think he'd ever seen that expression utilized in quite that manner before. It was unorthodox, but actually made a lot of sense if one chose to overlook the generally accepted usage for it. It was quite beautiful how it had been applied to the problem at hand, lending an elegant twist to the situation while not sacrificing any strength in the process.

The numbers started racing through his mind even before he'd fully decided to accept the project. Charlie opened the second folder and began flicking through it as an idea began to form in the back of his mind. It was crude and unlikely to work, but it was a good starting place considering what he'd seen so far and had the potential to develop into something, though it would take a lot of work. The math involved was of the highest level and he almost wished he could meet the person who had devised it as he was sure there was a lot that they could learn from each other.

There, that bit right there, which prevented anyone from simply hacking into the outer layer of the security features and allowing someone to upload a virus or other corrupting factor into the system to try and overwhelm it was another instance of beautifully structured brilliance.

This could be quite the challenge and Charlie knew he'd accept the offer. There was no way he could resist delving further into this and seeing what else this mathematician had come up with. It was glaringly obvious that the person responsible for this work was a mathematician and not some ordinary programmer with an advanced knowledge of mathematics; the expressions were far too elegant for that. There was clear understanding of the principles behind the concepts used, to the extent that the creator was able to use some of them in ways other than the immediately obvious.

"Dr. Eppes? Charles?" Banner questioned, trying to recapture the younger man's attention.

"Huh? What?"

"I assume that you'll do this consultation for us?"

"Yes, yes," Charlie said dismissively as he turned his attention back to the numbers, his mind already leaping ahead.

Oh, he hadn't realized you could use a Blowfish Cipher Algorithm with the No Cloning Theorem like that.

Friday, 18:36
Dr. Charles Eppes' Office, CalSci

Then, substituting theta for the unidentified variable would allow him to get past the first part of the security algorithm, but then it would-

Charlie frowned at the result that particular tactic led to. Spinning around, he scrambled about for the notes about that aspect of the programming. Where had he put them? They weren't where he thought he'd left them and he was forced to shift other piles of paper about on his desk before remembering that he'd been sitting on the couch the last time he'd flipped through the file in question.

A quick search of the papers scattered about the couch led to the successful retrieval of the file he needed. Absently humming a bar of his favorite music under his breath, Charlie scanned the notes, looking for the specific equation he was looking for. There it was, huh, he'd been right, that line of thought wouldn't work, not with the way the unknown mathematician had used the E91 protocol.

A frisson of frustration shot through Charlie at being thwarted yet again. He'd been working almost nonstop on the problem, but wasn't much further than he had been at the start. It was annoying even though some part of him reveled at the challenge the problem presented. It wasn't often that he got to go head to head with another mathematician of this caliber and he savored the experience.

Part of the reason he was having so many difficulties lay in the fact that he couldn't quite seem to get a handle on his opponent. Charlie was beginning to suspect that this whole system was not just the work of one person, but of two, or more, mathematicians. He could definitely see that the work of the person he admired the most was interwoven throughout all of the parts he currently had access too, as it was quite distinctive and unique, but there were other bits that simply didn't seem to fit. Well, at least not stylistically. The different parts all worked together seamlessly to perform the function for which they'd been designed, otherwise he would probably never have been asked to crack the system, but the styles were so very different.

Where one was elegant and beautiful to the point of almost being a work of art, the other, or others, were much more bland. The math was still firm, but much more predictable and thus easier to work with or to work around. Not that any of the theorems utilized allowed for much room to maneuver. The other people involved were clearly competent mathematicians or programmers in their own right.

The other thing that Charlie had noticed was that there seemed to be something else embedded into the secondary layer of the security system. He couldn't quite make out what just yet as he hadn't managed to peel the first layers back entirely, but he could all but see glimpses of it, as it were, in the effects it had on the expressions and algorithms which had been build up around it. It seemed familiar on some level, but he couldn't fathom where or why he would have run across that before. It bothered him for a reason he couldn't quite explain and caused him to frown.

With a sudden start, he realized that he'd been looking at the end of the first algorithm incorrectly. If he tried to approach it from the other end, that altered things entirely. As the numbers began to swirl in his mind, Charlie raced back to the blackboard he'd been working on and erased what he'd written earlier, grabbing his chalk and starting anew.

A knock on the door followed by a greeting from his brother abruptly pulled Charlie out of his thoughts.

"Hey, Don," Charlie replied absently before writing a few more lines on the board to ensure that he didn't loose his train of thought. "What brings you by?" he asked as he finally turned around and caught the smile on Don's face. "What?"

"Nothing," Don shrugged, the smile only growing before he gestured around at the papers littered all over the office. "Just that this looks much more like your usual workspace now."

"I've been busy," Charlie protested before frowning as he noticed the file his brother held. "Do you need help with a case?"

"Not a new, active one. I just got a call from Howard saying he needs you to further clarify the math you used to help David and the others to track down and arrest Slobodan Radovic."

"Radovic?" Charlie questioned, unable to stop his eyes from glancing down at the spot on his brother's chest where the man in question had stabbed him. "I thought Robin was working that case."

"At the time, yes, but it's been decided that it would be better if the public prosecutor leading the case wasn't personally involved with one of the two agents who was attacked and wounded," Don explained nonchalantly, as if he wasn't the one who'd ended up in the hospital, fighting for his life.

"I see," Charlie said tersely, angry at Don's continued inability to fully open up to him and their father about his injuries. "When does Howard need it by?"

"I'm not sure, the sooner the better probably," Don replied, his eyes moving past his brother to look at the blackboard he'd been writing on and it was all Charlie could do to not jump in front of it and try to prevent Don from seeing it.

Not only would that be suspicious, but pointless as well as he knew that Don wouldn't understand any of it anyway.

"Why? You too busy at the moment? I thought this was your calm time without the students about or classes to teach."

"That doesn't mean I don't have anything to do," Charlie said as everything that Banner had said about needing to keep quiet about this consultation came back to him in an instant. "There are lectures for the fall to organize, calculations for collaborators to work on, not to mention my own research."

"Ah, okay," Don replied though Charlie thought he detected something more in his voice.

Did his brother suspect that he was holding back on him? Was he really that easy to read now that they'd grown so much closer than before?

'You know you've never been really good at keeping secrets.'

Don's words from five years ago echoed through his mind. If he'd thought that when they'd only just started working together, then what did his brother think now? Would he have learned better by now or would that knowledge have been negated by an increased ability on his brother's part to read him? Charlie knew he'd never been great at masking his thoughts and emotions and Don had always been an excellent people person, his job honing the skill tremendously. Combined, that didn't make things very easy for him when he wanted to conceal something from Don, at least not when they were interacting with each other.

"Maybe it would be best if you give Howard a call and let him know it might be a few days," Don suggested as he handed Charlie the file.

"Ah, yes, okay."

"Are you going to be long? Dad's making brisket tonight."

"Huh?" Charlie asked, looking up from the file he'd opened for a quick look before he glanced at the clock in surprise.

Was it nearly seven already? He'd thought it was only four thirty or so. He'd obviously gotten lost in the math again, but the problem was such an interesting one, especially since that particular variable was still bothering him... If only the NSA would give him access to all of the information! Although, if he took x to be the ratio of-

"I'll take that as a yes, then?"

Charlie blinked, looking back at his brother, the earlier feeling that something wasn't quite right back.

"Yeah, yeah," Charlie finally answered just as it looked like Don might ask him again. "What are you doing here so early anyway?"

"Seven is hardly early," Don replied, frowning.

"Says the man who regularly works until ten or eleven."

"We wrapped up the case we were working on at one, finished the paperwork and didn't get a new one. Which is good as I've got the weekend off."

"Oh, you got any plans?"

"Yes, but don't tell Robin as I want it to be a surprise."

"I see, well, have fun."

"I'm sure we will," Don assured him, his face still troubled. "Are you sure everything is okay? You seem worried."

Charlie silently cursed his inability to hide his emotions better from his brother.

"Yeah, yeah, it's really nothing. The problem I'm working on is giving me some trouble and without Larry or Amita around to bounce ideas off of, I've got to try and figure it out on my own."

"Ah, I see," Don began. "Well, I'd love to help, but-"

"I know, I'm on my own for this one."

"See you later."

"Bye," Charlie replied absently as a new thought occurred to him.

What if he forgot about x for the moment and instead focused his attention on the exponential component of the algorithm? It wasn't the normal way of handling a problem like this, but given some of what the creators had done, he figured leaving the tried and true path just might be the key in this case.

Which still didn't explain why it all seemed so familiar or why the secondary component of it bothered him so.

Well, this round of the Write-Off got me to finally start writing a story that's been at the back of my mind for a while now. I'd not really started it yet as it really needed to be told at least partially from Charlie's point of view in order to work properly and I've always been a bit wary of doing that.
Oh, things mentioned here like the Blowfish Cipher Algorithm and the No Cloning Theorem are real, I just hope I managed to use them correctly. I tried my best with the help of Wikipedia, but it's not my area of expertise, so I can't guarantee anything.