A/N: Since I'm almost done writing this puppy, I can start posting it a little faster. Happy weekend!

Also, Chapter 6 is not exceptionally long; it's just split unevenly for maximum cliffhanger effect. (insert evil grin here)

Disclaimer and acknowledgments are once again in the Prologue.

ooooooooooooooooo

Chapter 6: You'll Never Walk Alone

Tuesday, April 29, 2008
8:33 P.M. (Eastern)
Washington, DC

Charlie turned the corner and strode on down the darkened street, grumbling to himself. Whoever had the bright idea to hold a major math conference in Washington, DC, at the same time that the cherry blossoms were in full bloom was an idiot. While the trees filled the Mall with fluffy, fragrant pink blossoms, they also filled the hotels with tourists. The conference hotel had been completely booked before he even registered for the conference, and now he was trudging a mile or more to the one hotel where he had managed to find a room.

He kept a wary eye out as he walked along the street. The neighborhood he was passing through wasn't the greatest, and although he wasn't spooked enough to take a cab from the conference center to his hotel, it didn't hurt to keep his eyes open. There were only a few other people out on the street, but they were also trotting along with their heads down, probably making their way home.

What was making him nervous was that here had been footsteps following behind him for a couple of blocks now. Come to think of it, they might have been following him for longer than that. He resisted the urge to turn around and look, not wanting to appear like a scared tourist worried about the big city streets. He did quicken his pace a little, and he was slightly alarmed when the footsteps kept up.

A few yards ahead was a traffic light, the walk sign turning from a white pedestrian figure to a flashing red hand. He broke into a light jog to get across before the light changed, and much to his dismay, the person behind him did, too. He glanced around worriedly, but there was no one else at the intersection, and since it was a residential neighborhood he was passing through, there were no stores nearby for him to duck into.

He stepped up onto the curb as the light changed and nearly jumped out of his skin when he heard a familiar voice speaking from a foot or so behind him. "What, have you taken up jogging or something, Chuck?"

Oh, my God. He stopped dead in his tracks, not daring to say anything unless it was just a figment of his imagination. Was that his brother's voice?

"Keep moving!" Don hissed quietly. "I'm going to follow you to your hotel, okay?"

"Yeah, uh, sure," he muttered over his shoulder, fighting the urge to whirl and fling his arms around the man standing behind him. Instead, he walked at an even faster pace for the remaining few blocks, his heart soaring with every step. He had to force himself to slow down as he approached the Doubletree and passed through the revolving door without a glance for the person following.

Charlie crossed the carpeted lobby and entered the elevator, waiting to press the button for his floor until the figure in a dark peacoat, navy baseball cap, and glasses had entered behind him. He noted the security camera up in the corner and looked down at the floor, pretending there was no one else in the elevator as if it were a stranger standing next to him. A couple entered just as the doors were closing, an older man with graying hair and a younger woman with dark blond hair and glasses. The woman was saying, "I think Senator Cantwell was impressed with your proposal, Dad, but I'm not so sure about Senator Murray."

"Well, she's never been as friendly towards business as she could be, so it's hardly surprising." He pressed the button for the seventh floor, and they continued their conversation as if the two of them weren't there. Washington, Charlie thought. It was all about who you knew and who you talked to. Kind of like academia, come to think of it.

The two exited at their floor, and Charlie waited impatiently for the doors to close. When the "ding!" sounded to announce their arrival on the tenth floor, he gave a little jump. He could barely hear the low chuckle coming from the elevator's other occupant, but the sound only confirmed that the person was who he thought it was. He walked calmly down the hall, looked in both directions to see if anyone else was in the corridor, and then slid his keycard into the lock and pushed open the door, gesturing for Don to walk in before him. He slipped in after him and waited until the door swung solidly shut.

The heavy curtains over the window were already closed, but Don checked them anyway. Then, as Charlie watched, he pulled the cap off his head and the glasses off his face. The familiar features were shadowed with stubble and the trace of too many sleepless nights, and he was leaner than he remembered, but it was unmistakably his brother.

"Don," he half-gasped, half-whispered. Then they were embracing, Charlie's eyes closing as he wrapped his arms around the person he'd missed more than he even realized. The Eppes family might not have been prone to hugging, but he felt in that moment that he was sharing months' or even years' worth of familial love. He felt Don grip him even tighter, and he rubbed his back soothingly, rocking back and forth a little where they stood.

After what seemed like several minutes, they drew back. "Let me look at you," Don said, ruffling his hair like he had when they were kids. "God, it's so good to see you."

"Yeah, it is," he echoed. "What…how…what are you doing here?"

"I heard this famous mathematician was giving a talk, and I didn't want to miss it," Don teased, the corners of his eyes briefly crinkling. Then he sobered. "Actually, I can't stay long. I just…" He gave a small shrug, then briefly looked down. "Would you believe I was in the neighborhood?"

Charlie put a hand on his upper arm and steered him towards a plush chair. "Why don't you tell me about it?" he said softly.

"Charlie, I really can't stay," Don protested as he sank into the chair.

"Just for a little while?" he pleaded. "Look, do you want some food? I didn't really eat dinner; I could order something from room service."

Don shook his head. "They'll wonder why you're ordering two meals."

"Then I'll order one big one." He put on his best puppy-dog expression. "Just for a little while," he repeated.

He could see the internal struggle Don was fighting playing out across his face as he consulted his watch. Finally, he acquiesced. "Okay, but not for long."

Then why did you come at all? he wanted to ask, but there was no way he was going to do anything to put Don on the defensive. He'd been given a gift here, and he wasn't going to ruin it.

He ordered a large steak and salad, throwing in a piece of cheesecake and a basket of bread for good measure. Don looked like he wanted to protest, but Charlie pointed a finger at him, and he didn't make a sound. If their father were there, he knew he would have some comments to make on Don's thinner build, but this wasn't the place or time for that.

When he was done, he hung up the phone and sat cross-legged on the bed, taking a moment to examine Don's features. His forehead had more lines in it than before, and his eyes were more haunted than Charlie had seen them except after a very difficult case. His entire frame radiated exhaustion but at the same time he had a watchfulness, a wariness about him that Charlie wasn't used to seeing in him. Oh Don, he thought sadly. What have they done to you?

Don must have seen him watching, because he looked away self-consciously. "How's Dad?"

Charlie shrugged one shoulder. "Okay. Well, as okay as any of us are, you know."

"No more problems with his heart?"

"No, he's been on high blood pressure medication and it's been working great. Millie kind of made it her personal mission to make sure he takes care of himself." He made a slight face. "He's been spending as many nights at her place as at home."

Don chuckled. "Hey, better there than at your place, right?" Charlie gave a rueful grin, and told Don some stories about Alan's latest clients. The business was going well, although their father had let Stan take the lead on most of their work because the name "Eppes" had been on the news a few too many times. He glossed over that part and hurried on to talk more about Millie and her latest changes to the math department at CalSci.

"How about Amita?"

Charlie looked down at the beige carpet. "We, uh, we've both been pretty busy lately." They hadn't patched things up after her ridiculous insistence that he turn Don's postcard over to the FBI, and the longer things between them were strained, the easier it was to slip back into their professional roles. Not that he had any notion of telling Don that; he'd probably blame himself for coming between them.

Don was studying him carefully. "I'm sorry to hear that, buddy."

"Yeah, well—" He started to say more, but there was a knock at the door.

Don was already out of his chair, gathering his coat and hat. He slipped past Charlie and into the bathroom, closing the door partially and leaving the light off. Charlie blinked. It was almost like he had never been there.

He opened the door, paid the attendant, and took the tray inside. It smelled delicious, and his stomach gave a small growl. He really had skipped dinner, but this was all for Don. He put the tray down on the table and went back to push the bathroom door open. "It's okay," he called softly.

While Don ate, he told him about the rest of his team. Megan was in charge now, partnered with a rookie from Kansas who was apparently overawed at being in such a big city for his first assignment. Charlie related the story of Matt's first takedown as Colby had told it to him, exaggerating the comic parts and minimizing the part where he had almost gotten himself killed. It produced the desired effect, and he went on, pleased at being able to bring a smile to his brother's eyes.

"Colby has been great," he said, nibbling on a piece of bread. "Everyone in the office knows not to say anything about you, or he'll just go off on them. Megan's not so overt about it, but she's been really supportive, too."

"She didn't get in any trouble, did she?" When Charlie frowned in confusion, Don went on, "I didn't know who else to call, but I tried to word it so that she, you know…"

"Oh." The initial news of Don's escape had been so long ago, he'd completely forgotten about it. "I don't think so, but I wasn't really spending much time around the office then. Megan's actually the one who, um, got me to come back and work with them again."

He looked up from underneath his eyebrows, hoping that Don wouldn't be upset by that fact. But he finished chewing his steak and said, "I'm glad you are, buddy. There's a lot of people out there who need your help."

"No one as much as you," he said, raising his head and looking at Don straight on.

Don indicated the plate in front of him. "I can't ask for more than this," he said.

And then an idea flared to life, and he smacked himself in the forehead for not thinking of it sooner. "Actually, I can do a lot more for you than that."

His brother's expression had turned wary. "What do you mean?"

He grabbed the backpack that he had discarded on the floor after entering the room and pulled out his laptop. "I've been working on a project that I think can help you find Alex Brock."

"How did you know I'm looking for him?"

He gave a quick shrug as he booted up the laptop. "I know you. You didn't go on the run to avoid being in prison. You're trying to find the person who really killed Liz. You think that's this Brock guy, and since the last time anyone saw him out of jail was in Richmond, that's probably where you've just been."

"Yeah, and all for nothing," Don muttered.

Charlie gave him a sympathetic look. "I figured that, or you'd have been in contact with Megan already."

He looked up to see a slow smile spreading across Don's face. "I've missed that brain of yours, Chuck."

"Don't call me that," he said, rolling his eyes. It was easily the most half-hearted protest he'd ever voiced.

There was silence for a moment as the laptop flickered to life. Then Don's voice broke in. "So, you didn't mention David."

"Oh." Charlie typed in his password. "Yeah, uh, he's decided to stay."

Don's voice was probing, the same tone Charlie had heard him use in the interrogation room on more than one occasion. "There was some question of that?"

Crap. He'd somehow forgotten that all of this would be news to Don, and not the good kind of news, either. "Uh, he wasn't sure for a while, but yeah, I think Colby talked him into staying." He busied himself with opening up the program.

"I see." There was silence, and then he said in a softer tone, "Come on, Charlie, spill."

He looked up into his brother's eyes. There were so many things he had saved up to tell him if he ever got the chance; there was a whole mental file of "stuff to tell Don" that he kept locked away rather than agonize over how much he wanted to share it but couldn't, everything from a case he had helped the team solve to something funny yet profound that Larry had said. He didn't want to waste any time they had together on something this potentially awkward. But at the same time, as his eyes searched Don's, he realized he didn't want to hide anything either.

"Okay." He took a deep breath and chose his words carefully. "See, after you…well…left, there were kind of mixed opinions about whether that was the right thing for you to do. Colby came down on one side, and David on the other, and…it was pretty awkward for a while."

"What about you?" Don asked quietly, his eyes boring into Charlie's.

Perceptive as ever, Charlie grumbled to himself. His hands stilled on the keyboard. "I'm not going to lie to you," he said at last. "I was kind of angry at first, and I guess David was, too. I just…I mean, I was working my ass off, Don, every spare moment I wasn't in class, and the three of them were staying in the office every night and every weekend after they finished the crap work they were stuck with, and we knew that sooner or later, we were going to find something to clear you. It had to be there, somewhere, but we were going to find it. And then—" He spread his hands. "And then all of that work didn't matter."

"Charlie." Don's face was pained. "It's not like I planned it, you know? I—there was this chance that opened up in front of me, and I knew it wasn't the greatest idea, but I couldn't turn it down. I wanted to believe that you guys were going to find something, honestly I did, but it all happened so fast, and then—"

"I know," he replied quickly. "I don't blame you at all. I got over that really fast. I…I can't even imagine what it's been like for you."

Don grimaced. "Yeah, well, it's been harder than I thought it would be. And that's really saying something."

"Well, let's see if this can help." He brought the laptop over to the table and drew up another chair. "It's something I've been working on for almost a month now, and I finally got it. I was going to test it one or two more times, but now…." He couldn't resist the impulse to lean over and give Don a one-armed hug. He was relieved to see a smile curl the other man's mouth, and to get the hug returned.

"Okay, tell me what you got."

"All right, so there's two parts to this, both elements of facial recognition software, or FRS. You're familiar with how that works, right?"

"Yeah, based on the news reports, that's how they found me in Ontario," Don muttered.

Charlie shook his head. "No, I think some poor rookie had to sift through hours of surveillance tapes. At least, that's what Megan told me, although her information was already secondhand. FRS has a lot of difficulty with three-dimensional images, although they're improving it all of the time. No, what I mean is more standard two-dimensional images: photographs. Remember that case in Claremont where you found the fourteen-year-old girl who'd been kidnapped by her father when she was eight?"

Don's brow furrowed and then cleared. "Yeah, Melissa Williams. Our tech guys were able to kind of fast-forward her second-grade picture, and one of her teachers saw it on the news."

"Right. See, you can think of every human face as a combination of a standard set of eigenfaces, which we get from a principal component analysis of the eigenvalues of a covariance matrix of a known series of faces." He saw the blank look and rushed on. "There's only so many possible configurations of our features, and we can start from a set of the most common and describe any face as a combination of those. There's certain nodal points that aren't going to change if you gain weight or age, like the width of your eye sockets or the curve of your jaw." He gestured toward the glasses and cap sitting on top of the dresser. "That's why glasses are surprisingly effective as a disguise; think of Clark Kent and Superman."

He paused, struck by the almost wistful look on his brother's face. "You have no idea how much I've missed this," Don murmured.

"I know. No one nods and pretends to understand what I'm talking about better than you." But his throat seemed to be closing around the words as he spoke them, and he had to look away.

After a moment, Don said, his voice also suspiciously thick, "Go on, Chuck."

"I told you," he warned, but he appreciated the jibe as a way to clear his head. "So. These nodal points don't change much as we age, unlike, say, your cheek or your forehead. We can take a child's face and, keeping the nodal points the same, alter other features like the height of the forehead or the fullness of the cheeks to simulate what they look like as they age."

"Like with Melissa."

"Right. Now, the most common application of this method is finding missing children, so that's where programmers have concentrated their efforts." He gestured at the screen between them and tapped a few keys. "However, with a little adjustment, there's no reason we can't do the process in reverse."

A face appeared on the screen, and out of the corner of his eye, he saw Don stiffen. It was a mug shot from the Richmond, VA, police for Alexander Brock. He cast Don a slightly nervous glance and went on, "First of all, the difficulty comes in switching between 2D and 3D images. That's where something called surface texture analysis comes in. You can take a picture of a patch of skin and break it up into smaller blocks." He clicked on an icon, and the screen zoomed in to an extreme closeup of Brock's forehead. "Once we do that, we can measure distances between pores, the depth and position of wrinkles, and other unique characteristics."

Don had the familiar knitted brows and pursed lips that indicated he was following so far even if he didn't know where this was going. "Kind of like a fingerprint."

"Exactly. In fact, it's called a skinprint. And by comparing skinprints from different sources, like different photographs, we can greatly improve the match we get. So, for example, if we take that image and compare it to this one—" he opened a second window with a photograph that was clearly a still from a surveillance camera of a man with a baseball cap and goatee— "even if the facial features like the jawline are hard to match, we can compare skinprints." He clicked on another icon, and the screen zoomed in on the new image and showed a 100 match.

"Huh." Don's expression had turned more distant. "So, how many law enforcement agencies use this?"

"Not many. It's being developed by private companies, so it's up to individual agencies to purchase it, and depending on their budgets…" Charlie trailed off as he realized that Don had asked for a more personal reason. "Oh. Er, it's still largely in the trial stages. It's not really that common. I was able to replicate it with some work, but I don't think there's many other people who would be able to."

He received a sharp, probing look in response. But all Don said was, "So, what have you been doing with this?"

Charlie cleared his throat. "Well, I've combined it with a search engine that a colleague of mine has been developing to search images on the Internet not by image tags, but by the image itself. See, if you go onto Google and search for a picture, you're going to get results based on the text around the image or the filename that the user gave it when they uploaded it. So you can get some pretty weird results. It would be much better if you could search for something like the Eiffel Tower and have it pull out pictures matching this shape," and he made a swooping gesture with his hands to indicate the half-curved sides of the iconic tower.

Don's eyes had that glint that indicated he was matching Charlie's mental leaps. "Are you telling me you've managed to find images of Brock online based on the shape of his face?"

"I haven't tried yet, because I was trying to take it a step farther." He switched to another program, again showing Brock's mug shot. "I mentioned running the aging process in reverse." He clicked on the picture, and it started transforming: the forehead shrank, the cheeks grew smaller, and they were soon looking at an image of a teenage boy, not the killer he would become.

The furrowed brow was back. "I'm sorry, but I don't see how that helps. I'm looking for him now, not as a kid."

"Ah, that's where you're wrong." He turned to face his brother. "Alexander Brock was something else before he became a hired killer. He was someone else." He paused and watched, hoping to see the light bulb come on over Don's head.

He was disappointed. "Charlie, they already searched all of his known aliases."

"That's right. All of his known aliases." He opened a web page and typed a few lines into a command box in the middle. "What if we missed one?" He pressed "enter," and the browser went blank before showing a series of three faces.

Don peered more closely at the images, which were from the Chicago Sun-Times' online archived issues. He reached out to the touchpad and switched back to the program with a younger version of Brock. "Oh, wow," he said softly.

"If you compare these," Charlie said, switching back to the images from online, "using surface texture analysis, they are a match. You're looking at Alex Young, born and raised in Chicago, who later became Alex Brock."

Don sat back and thought for a moment. "Have you had any luck searching for Alex Young? Or for more recent images of Alex Brock, after 2005?"

"I haven't tried." He looked down at the floor. "I was too busy preparing for this conference. I haven't run the name through the FBI database, either; I'm sorry."

"Hey, it's not like you were expecting to run into me, huh?"

He looked up. "No, not exactly," he admitted softly as he felt a smile stretch across his face. "It's so good to see you."

"Yeah," Don agreed, his smile lingering for a moment before turning sorrowful. "You too, buddy. It's been great." And he started to rise from his chair.

"Wait," Charlie said, bounding to his feet. "You're not going?"

"I have to, Charlie. I…I shouldn't have come at all, but to know that you were so close and not try to see you…" He turned around and picked up the coat hanging over the back of the chair.

"Don, I—" His mind whirled, trying to think of something. "I have to get up early for the conference. You can stay here tonight and leave early when I do. No one will ever know."

"You can't know that," his brother responded quietly. "You have no idea who might wonder why there are voices coming from a room booked by a single person, or who might be reviewing surveillance video and notice something unusual, or who might walk by the room and see two shadows moving where there should only be one."

"It's a hotel. I'm sure there're plenty of rooms with two people in them when there were originally supposed to be one. Look, we can talk some more, figure out what we're going to do next."

"We are not going to do anything next. Charlie, you have no idea how much I appreciate this," and he pointed at the laptop. "But I can't be in contact with you, I can't be talking to you. It hurts like hell that I don't know when I'm going to see you again, but that's the way it has to be."

He restrained himself from mentioning the postcards, hoping that Don wouldn't say that he had to stop sending those as well. He looked beseechingly at his brother. "You can't do this alone."

"You don't understand." Don planted his hands on the table and leaned forward, his eyes intense. "This isn't about me being stubborn and refusing to accept help. This is about what it means for you to get caught helping me. It means the end, Charlie. The end of your security clearance, the end of your job, and quite possibly some time in prison. Javier would love to put you behind bars if she can't get me. Do you get that?"

Charlie drew in a deep breath. He knew the implications of having Don there in his hotel room, at least in an abstract sense. The part of him that was confident his big brother would never do anything to put him in danger was wavering, realizing that he didn't always make perfect choices, and that maybe he would do well to listen to his head instead of his heart here.

On the other hand, no one said that you couldn't do both at the same time.

He spoke quietly, confidently. "Listen, it's still before ten o'clock. If you wait a couple of hours, there'll be fewer people coming in and out of the hotel, right? That means less chance of you being seen. You can, I don't know, take a shower or something."

The corner of Don's mouth turned up, almost in spite of himself. "Is that a hint?"

Charlie felt his shoulders relax. "Well, it might not be a bad idea." He had another idea of his own, and it was only going to work if he could get Don out of the way for a few minutes. "I'll just finish up with this program, okay?"

Don dropped his coat back on the chair with obvious reluctance. "I'm out of here by midnight," he said pointedly.

He spread his hands. "Whatever you say."

He watched as Don made his way into the bathroom and shut the door. He waited until he heard the water come on, then scribbled a note about going to the vending machine and slipped it under the door. Hopefully, he'd be back before Don even knew he was gone. He'd noticed an ATM in the lobby earlier, and even if he couldn't persuade Don to shelter there for the night, he could give him a little help on his way. He knew that his bank accounts were probably being watched, but based on the cases he'd consulted on, he knew that they were being watched for maximum withdrawals, and he knew what those limits were.

No matter what his brother said, he was not going to let him go through this alone.

ooooooooooooooooooo

6:55 P.M. (Pacific)
L.A. FBI Field Office

Tom Metzke leaned back in his chair and cracked his neck. It was well past quitting time, which probably explained why he was almost the only agent left in the bullpen. With Javier closing things up in DC before making her permanent transfer to L.A., he and Chad Danvers had been keeping fairly standard hours for once, no racing off to distant states at a moment's notice or poring over camera footage until their eyeballs hurt. Not that he didn't want to do whatever it took to find Don Eppes and put him back behind bars, but he wanted a life, too. He had one more thing to look up, and then it was time to go home.

The computer in front of him dinged, and he looked up. A window had opened in the upper left corner, and he clicked on it. As he read, he slowly sat up straighter. He opened up a web browser and checked a few pieces of information. He pursed his lips. Could Eppes really have been so dumb, after all this time?

No matter. They had a great chance here, and by happy coincidence, they could have him before he even knew what hit him. He picked up his phone and dialed Dina Javier's cell number. Surprisingly, it went straight to voicemail. "Hey Dina, it's Tom. One of our little tripwires found something. Charles Eppes just withdrew funds from two different bank accounts, under the maximum amount, but within minutes of each other. And you'll never guess where. It was the ATM at the Doubletree in central Washington, DC. I'll, uh—" He stopped as a thought struck him. "I'll check back with you later."

He hung up and thought for a moment. Then he hurriedly switched off his computer, packed up his desk, and made for his car. At the usual location a few blocks from the office, he pulled over to the curb and fished out a small slip of paper from his wallet. Hesitating for only a moment, he dialed the number.

"Hello?"

He paused, not knowing what to say. How did one address a hired killer? "Uh, this is Metzke. He's at the Doubletree Washington, DC."

"You're sure?" The voice was clipped, precise.

"Well, no positive ID, but our records indicate suspicious activity on the part of his brother who's registered there."

"I see." There was a rustling sound in the background. "I can be there by morning. Tell your Director that I'll call when I have him."

"Okay—" The other man hung up, and Metzke was left staring at the phone. He slowly folded it closed.

That had been surprisingly easy.