Hello! I wasn't intending to write another fic. before I'd finished my others, but the idea for this was stuck in my head and I had to write it down. And I couldn't stop until it was finished, so I figured that it wouldn't hurt to put it up here, considering it is finished and can update whenever I want. It's really short, only 4 chapters. So, let me know what you think, and if I get enough reviews and subscriptions I'll upload the next chapter.

I understand that not everybody will like this. If you don't like the idea, then please don't bother reading it. It's a waste of your time, and I'm sure that there is something much more enjoyable for you out there.

Please Note: I have absolutely NO CLUE when it comes to the C.I.A. All of the stuff about them in this fic. is completely made up, so please don't hate me for my lack of knowledge.

Set in season 2, because that's all that I've seen up to.

"Hey Don, check this out," Colby said, handing Don the notebook he'd just found in the victim's pocket.

They were at a crime scene of a young woman's murder. Multiple stab wounds to the chest. It would seem that the cause of death was loss of blood. No surprise there.

Don flicked through the notebook, taking in scribble, some nonsense words and a lot of numbers.

Everything was in there, from equations to complicated looking graphs.

"Looks like it's time to pay my brother a visit."

It was morning, but Don was hoping that Charlie hadn't left for CalSci yet. Hopefully he would be able to catch him on the way out of the house.

The agent stepped out of his car and walked casually to the door, letting himself in.

The surprise that greeted Don was two men in suits wearing dark sunglasses. What would they be doing here?

Don very subtly moved his hand to position it on his belt, in a way that his jacket was pushed to the side so that his F.B.I. badge was revealed. "Can I help you gentlemen?"

"We're looking for Agent Eppes." The man who said it didn't show any emotion at all, and spoke in a monotone voice.

"Yeah, well you found him."

The men didn't even speak a word. The first one, who spoke beforehand, grabbed Don's arm and twisted it around his back, while the second grabbed his gun and aimed it at him. The federal agent hadn't even had a chance to move.

"I think you should come with us, Eppes."

Charlie stood in his office at CalSci, headphones on, scraping chalk against one of many blackboards in the room to form numbers, symbols and equations. He took comfort in the numbers. They gave him something to do with his mind, so that he wouldn't think of things better left alone...

A phone disrupted his mathematics – though he wouldn't have known if not for the vibration in his pocket, due to the volume of the music.

He sighed when he saw the caller I.D. He'd thought that he'd finally gotten away from these people. Apparently even his refuge in numbers couldn't stop those memories from coming back. Well, of course they couldn't when these people kept calling him.

Sighing again, he flipped the phone open, and spoke as he put the device to his ear.

"I told you, I'm not going back into the program, so you can completely forget it. Stop calling me."

"This isn't about the program, Eppes," the voice on the other side of the phone told him.

"Well, what else can it be about? Why else would you call me?" Charlie ran a frustrated hand through his hair. When would they learn?

"Your brother was kidnapped this morning. By two men involved with the group you...took care of in Mexico."

Charlie dropped the chalk which he still held in his left hand.

"As far as we can tell," the voice continued, "They think that he is you. "

"Okay," Charlie said, finally coming to his senses, "How would they know who I am? Isn't that top secret information? How did they get hold of it? And what are they doing to Don?"

"We don't know, Eppes. We're still working that out. And we don't know what's happening with your brother, but we need to send an agent after him. There is no way that we're letting the F.B.I. handle this one."

"And you figured that you'd call me," Charlie finished.

"You've dealt with this mob before. You know what they're like."

"So it never even crossed your mind that I told you I'm never coming back to the C.I.A.?"

"I know you, Charles. This is your brother we're talking about. You've got fifteen minutes to get to HQ before your briefing."

Charlie sighed as the man cut the connection. He was right, he would do anything to get his brother back.

Time to go back.

David walked through the F.B.I. office to the board on which Megan was pinning photos from the crime scene.

"What you got?" Megan asked.

"Not a lot. 20 years old, working in a small store. No known enemies," David passed the file he had on the girl to Megan, and she started flicking through it as they walked back towards their desks.

"What about the notebook you found at the crime scene? Anything from Charlie?"

"Colby said that Don was dropping it off a couple of hours ago. I haven't seen him all morning."

"Hey, you guys seen Don?" Colby asked, right on cue.

Megan shook her head, "You were the last one to see him."

"He's not answering his phone," Colby told them.

"Oh. Well, what about Charlie?" Megan asked.

"Also not answering."

"Well, I'm sure there's a good reason," Megan reassured him, "He'll turn up."

Charlie stood in the office of the C.I.A.

And it was not good to be back. In fact, he was quite sure that he would never have returned if it weren't for his brother.

"Agent Eppes," a tall man with dark hair greeted him.

"Ex-Agent," Charlie corrected.

"I thought you were returning to go on a search and rescue," the man said, confused.

"I'm not returning. I'm finding my brother, and getting out of here," The Professor's usually soft eyes as hard as stone.

"How can you do it?" the man asked as they walked through the headquarters to the briefing room, "Just leave it all like that. After all that work, all that training. Don't you miss it?"

"I'm not built for this job, Stark." Charlie told the agent he had worked with a long time ago.

"Unless your brother is kidnapped."

Charlie answered with silence, stepping through the door and into the room in which he would be given a briefing.

"Hey, have you guys seen Don? Or Charlie?" Alan asked the agents in his son's office.

"Wait, you haven't seen them?" Megan asked.

Alan shook his head. "Haven't seen Don since he left for that crime scene. Charlie left for CalSci but he's not there."

"Huh," Megan tried to ring her boss again.

No answer.

Agent Stark briefed Charlie on what they knew about the case.

Two men had escaped from Mexico when Charlie was there, and decided that they'd get some revenge for the loss of their friends, by kidnapping Charlie. They'd already had threat letters, but Charlie wasn't interested in anything that the C.I.A. had to say to him.

"They've been sighted here, here and here," Stark said, pointing to several red dots on a map, "But the trail stops dead here."

Charlie's mind was already seeing patterns, forming equations and algorithms to find where they might go next, or where they might be hiding.

"What do you want me to do?" he asked, looking up at the agent.

"Rescue your brother. The F.B.I. would never let us live if he wasn't found unharmed," Stark received a glare from Charlie for this. There were more reasons than that for Don's safety, "Deal with the men whatever way is necessary."

Charlie nodded. He'd received a lot of similar instructions from men like Stark in his short time with the C.I.A.

"Better get started," Charlie said, and moved straight to the whiteboard which sat behind stark.

He picked up a marker and started writing down the numbers in his mind, checking back at Stark's map at regular intervals.

"What are you doing?" Stark asked, bewildered at the ex-agents sudden will to do maths. Surely now was not the time...

"I'm designing an algorithm to find the most likely location for the men to be hiding my brother," numbers and symbols were madly being added to the board.

Stark looked confused. "What exactly do you do now?"

"I'm a professor of Applied Mathematics. And I consult with the F.B.I."

Stark nodded sharply. The boy always had quite a gift in maths. That's why he was in the program to begin with.

"You sure there's only two men?" Charlie asked. He had to have as many of the variables as possible.

"Well, there was two to start with. There might be more now."

Charlie added this into his equation, and then picked up a texta and started drawing dots and lines on the map. Usually a process like this would have taken days, maybe even weeks, but consulting for Don had meant that Charlie was doing this sort of thing quite often.

"What's that?" Stark asked.

"After your sightings," Charlie said, "They would have been here and here. I'd estimate an 87% chance that Don's being held in this area," Charlie circled the area on the map as he said it, "I need to see the buildings to know which one's the most likely."

Stark nodded. "Good luck, Agent."

"Ex-Agent," Charlie corrected as he walked out the door.

Don's eyes flickered open and he slowly came to his senses.

He could barely see a thing, it was dark. He remembered going to his father's – no, brother's – house, in search of the mathematician, and found the two men there. Who were looking for him, and knocked him out pretty much as soon as they found out who he was.

That story was backed up by his throbbing head.

He heard the clunking of furniture, and then footsteps.

Knowing that somebody was coming, Don decided to work out his complete situation as soon as possible.

Checking his belt, he realized that he didn't have his gun or his F.B.I. badge. His phone was also missing.

A man entered before he had a chance to search the room, flicking on a light and temporarily blinding his hostage.

"Special Agent Don Eppes, is it?" the man asked, flicking Don's badge and I.D. onto the ground in front of him, then continuing to talk before Don had a chance to answer, " You know, you caused a bit of trouble for some friends of mine when you were in Mexico."

Mexico? Don had never been to Mexico. "I think you've got me confused with somebody else," he croaked.

The man gave a snide laugh. "No, I don't think so. We have confirmation that it was Agent Eppes. I must say, for a secret agent your name was rather easy to find."

"I'm not a secret agent," Don said, confused. Did secret agents even exist?

"Not anymore, no. Looks like your with the F.B.I. now. Bit of a step down from the work you were doing before, don't you think?"

Frankly, Don had no idea what the man was talking about, but it didn't seem that he would be able to convince this man of that.

"What do you want with me?" he muttered grimly.

"Oh, it's not what I want," the man replied, A friend of mine who was in Mexico that day, he just got out of prison. And he wants his revenge. All I have to do is keep you here until his crew get here tomorrow."

Great, they had back up coming. Just what Don needed. He just hoped that his team would work out that he was gone and found him quickly. Surely that wouldn't be a problem when they had Charlie on their side.

In the meantime, he had a bit of a mystery to solve.

Who was Secret Agent Eppes?