I'm back! So, This is my first time posting a Numb3rs fic, and my first crossover fic, so bear with me here! My NCIS muse vanished a while back, and this is my attempt to woo her back so that I can finish A Past Come Back to Haunt. Never fear, I won't ever abandon a story, it just may take a while to finish.

This story takes place during season 5 of NCIS and season 4 of Numb3rs. Since my NCIS muse is gone for now, the story may be a bit heavier on the Numb3rs side, but I will try to give as much equal time as possible to both stories.

Disclaimer: I own nothing! Except this laptop...

4 days

2 Agencies

8 Agents

1 mathematician

Charlie was packing a bag, and looked annoyingly at his older brother, Don. "Don, I've had this trip planned for a week now. I'm not canceling it. You have heard of cell phones, right? Email? There are a lot of ways to get a hold of me if Amita can't figure out a way to help. I've given you all of the information that I know. If that isn't enough, you can get a hold of me." He zipped his duffle and grabbed his laptop bag.

Don nearly laughed as his brother picked up both bags. His carry on laptop bag was the same size as his bag that he was going to check. His brother was never without that laptop, though this time, that was probably a good thing if they needed to get a hold of him. "Are you sure you can't hold off on the trip until the case is cleared?" He was begging here, and he knew it. Hated it as well. How long had it been that he was relying on his brother to do his job for him? He didn't like this, but there was a lot of computer work involved in this case, and Forensics was backed up with the Russell Labs embezzlement case.

Just as Charlie was about to answer, his cell rang. Looking at Don, he answered. "Charlie Eppes. Hey, McGee how's DC? I know, just wondering if I need to bring my coat. That's true; LA has turned me into a wuss for the cold East weather. Yeah, my flight schedule hasn't changed," he said, directing that to Don as much to the Agent on the phone. "Thanks, I appreciate you willing to pick me up. Should I call you when I land?" Then he laughed. "Very true, you'd know if I was running late before I would. Okay, I'll see you soon," he said and hung up the phone.

"Charlieā€¦" Don tried one last time, but Charlie interrupted.

"Don, I'm sorry that this timeline got so messed up, I wasn't expecting this case to take so long. But I haven't seen Tim in years; last time I saw him was at MIT when I was giving a lecture and he was getting another degree. He's going to pick me up at the airport unless he gets called out on a case."

"So, what agency does this guy work for again?" Don asked, giving up. He'd agreed to drive Charlie to the airport so that the mathematician didn't have to leave his car there. The two climbed into the SUV.

"He works for NCIS. He's been a field agent for a few years," Charlie said as they drove off.

"Navy cop?" Don asked with a smile. In truth, he had nothing against NCIS. He hadn't worked with them personally, but some of his agents had, and apparently they were a good sort.

Charlie laughed. "Yep. Wish we had someone like him at the FBI. He's a computer geek, as you would put it, but he's been a field agent for years. I actually talked to him on the phone two years ago. I'd heard that a member of his team was killed during a case, and I was worried it was him."

Don winced. He didn't know what it was like to lose a member of his team, thankfully, but had known enough agents that went down that he didn't envy Charlie's friend. "They were close?"

Charlie sighed. "Yeah, pretty close. He was really broken up about it. She was the only female who treated him like an agent rather than a glorified computer, as he put it."

That hit a little too close to home for him, since he knew a lot of people who thought of Charlie that way. Thankfully his team knew Charlie well enough by now and that wasn't an issue for them. Charlie was a member of the team in his own right after all of the cases he had closed for them. Actually, over the last six months when there had been a lull for the Violent Crimes Squad, Charlie had gotten the team to look at some cold cases that he thought his math could help with. The team hadn't been thrilled, but it was better than paperwork, which is what they would have been doing. Turned out to be a good idea of Charlie's; before they got a new case, they had solved six cold ones. Even some of the other teams started looking at Charlie as part of Team Eppes. He knew that Director Merrick wasn't happy about having Charlie on the team; but after that, there had never been any complaints about using a consultant almost full time for Don's team. So far, they had never failed to close a case with Charlie's help.

"So you'll call me when you land in DC, right?" Don asked, to break the silence.

Charlie couldn't resist rolling his eyes. "Yes, Don. I will call when I get to the hotel. If anything exciting happens, I will call, and I will let you know when I am headed to the airport to come home, so that I know you will pick me up, or send someone to do it if you are out on a case. Oh, and I also left the number for the hotel, Agent McGee's work and cell numbers, too."

Don laughed. He knew that his brother thought he worried for no reason, but he did take it in stride, which Don was grateful for. "Thanks buddy."

Charlie smiled. He loved it when Don called him that. It was a bit childish to be happy about a nickname, but this one had some history to it, and was only pulled out on occasion. "No worries. Just don't be harassing Tim for no reason, I doubt his boss would like an FBI agent hassling one of his team. From what I've heard, the guy makes you look human," he joked.

Laughing with his brother, he pulled up to the airport. "I'll email you if we need some help, or if we manage to close the case."

Charlie nodded, and was about open the door to leave, but was stopped when Don pulled him into a hug. They weren't an affectionate family, though they did love each other, and hugs were rare between the brothers. Charlie squeezed him back, and then opened the door. "I'll see you before you know it, Don. Take care."

"You take care too, Chuck," Don said with a wink, knowing his brother hated the name.

Charlie playfully growled at his older brother before disappearing into security. Don turned the car around to head back to the FBI. He didn't know why, but he had an uneasy feeling about Charlie's trip, and would probably be worried until his brother landed back at LAX.

A/N: So, let me know what you think of the idea! Comments and suggestions are always welcome :-)