A/N: Well, I'm back! After a week of gaming convention, and a couple weeks of writer's block. Thanks for sticking around, Zillah seems to have done her job and hunted down my muse again, so updates should resume. This chapter, admittedly, is a little choppy, but at least it's written. I may come back later and re-do it so it flows better, but then again I'm extremely lazy. Consider yourselves lucky that I'm writing at all to begin with.

We're skipping ahead now, to Sniper Zero, because I'm interested in how Charlie and Edgerton will react to each other. Or, more accurately, how you lot will react to their interactions. Starts off following the ep pretty closely – then takes a major veer off into AU-land, which I'm sure will please a lot of you.

And I know that most of you won't like the way it ends, just… please don't lynch me until the whole story's over. You never know what's coming in later chapters.

Chapter Four: Guns 'N' Numb3rs. In which our favourite mathematician meets our favourite sniper, and sparks fly.

-BD-

As the months passed, Don and Charlie gradually found an acceptable balance in their working relationship. Don was still incredibly protective of his little sister, but he was resigned to the fact that he couldn't always prevent her from inserting herself into investigations.

Such as now. Don was busy talking to David about the dead mailman, whilst Charlie had swiped a police officer's clipboard and was estimating shooting positions. She smiled slightly to herself, knowing that Don didn't want her to be at the crime scene right now. But she was curious – she couldn't help herself. Charlie figured that one day her curiosity would get her into trouble, but right now she didn't really care.

She'd deal with that day when it came.

-BD-

Charlie bit her lip and fumed as she wrote furiously on the chalk-board. That Edgerton really got on her nerves! Sure, he was good looking, and intelligent, and got on well with Don… she sighed and paused in her writing, not really hearing Amit and Larry talking behind her. Face the facts, she thought to herself. He may be an arrogant bastard, but you find sniper-guy fascinating and attractive.

Shaking her head, Charlie tuned back into the conversation in time to hear Larry mention his aunt being afraid to leave the house.

"Why don't you tell your aunt," she suggested, "that statistically speaking she has more chance of being mauled by a bear."

"Actually," Larry mused, "statistics would favour the bear being mauled by my aunt, but…" Charlie laughed, remembering some of the other stories about this aunt. Larry had a good point. "This fear, this reaches beyond the realm of statistics, Charlotte." He sank down onto the couch and made himself comfortable, settling in for a long discussion. "This is about arbitrary, inescapable death. Y'know, times like these, you just wind up speculating about paths not taken, jobs left undone…"

"Larry," Charlie said with a small pang of guilt, "I… I'm trying to get those equations done for you, as soon as I can."

"No, no, no," Larry waved a hand in dismissal. "At that moment I was actually thinking of a far more prosaic legacy. Someone to carry on the Fleinhardt standard."

Charlie raised her eyebrows in astonishment and shared a glance with Amit. He looked just as surprised, and also a little devious.

"I didn't know you wanted kids, Larry," Charlie said thoughtfully.

"Well," Larry continued toying with a ceramic plate, unable to meet her gaze. "Children are wormholes. They're portals into the unreachable future and unattainable past. As things stand, though, they exist only in the theoretical realms."

Charlie stifled a laugh and turned back to the blackboard, whilst Amit continued to watch the despondent physics professor.

"Y'know," he started, and Charlie bit back a groan. She knew that trouble-making tone of voice. "Charlie threatened her father once with asking you to be a sperm donor for her own kids."

"Really?" Larry looked surprised. "Do you want children, Charlotte?"

"It was a joke," she glared at Amit. "A joke to get Dad to shut up about me producing grandchildren for him."

"Ah, that sounds far more likely," Larry nodded. After all, Charlie may have been a beloved teacher to many, and a brilliant mathematician, but she was rather lacking in maternal instincts.

-BD-

"Invisibility is a sniper's greatest strength. If he starts to worry about losing it, his heart rate increases. If he doesn't know how to handle that, his breathing rhythm gets thrown off."

Charlie could hear the words, but didn't really comprehend them. After all, Edgerton was standing so close behind her that she could feel his breath on the back of her neck. She could feel her own heart rate speed up, as her eyes fell shut and his half-whispered words washed over her. He had the most amazing voice.

It was then that she noticed it. Edgerton's breathing was slightly off as well. Was the proximity unnerving him, too? Forcing her eyes back open, Charlie looked down and saw Don looking around. He was probably looking for her. She bit back a sigh and stepped away from the window, lightly brushing against Edgerton as she did.

Just for a moment, she was certain that she heard a hitch in his breathing, and allowed herself to think that she was affecting him just as much as he affected her.

-BD-

That night, Charlie was trying to concentrate on both her calculations and her closest friend. It was no easy task, even at the best of times. Now, though, it was even harder, as the only thing that kept running through her mind was Edgerton.

"You know, at times like these," Larry commented as he set down a glass of cola in front of Charlie, "an empty house is not a home." He paused as she sent him a sympathetic look. "I've been evaluating my immediate prospects for a conventional nuclear family. I've just now begun to consider adoption."

"How long have you been considering that?"

"Three days."

"Give it a few more days," Charlie stifled a laugh.

"Yeah," Larry ran his hands over his face, and Charlie gave him a tender smile.

"Tell you what," she suggested. "Think about it for a month, and if you still want kids… we can talk about my threat."

Larry paused, trying to think, then beamed at his protégé. Charlie allowed herself a chuckle, before turning back to her calculations. Truth be told, she did want kids eventually, the timing had just never been right. That, and she had yet to meet a man she would like to start a family with. As sad as it was, her friendship with Larry was the most stable relationship she'd ever had. The most stable, and the longest lasting.

The pair turned back to the case, and after a few comments, Larry pointed out that she needed to 'insert a human element'.

"You sound like this Agent Edgerton guy," Charlie muttered, hoping that Larry wouldn't notice how she smiled when she said his name.

"Agent Edgerton?" Larry queried. He hadn't heart that name before – and didn't miss the small smile.

"He's a sniper instructor that Don brought in from Quantico. He thinks I should be out shooting rifles."

"Well why aren't you?" Larry exclaimed.

"It's… it's a poor allocation of my time," Charlie protested, grabbing at the first thing that came to mind. "In the time it takes to shoot X amount of bullets, I can access ten, twenty, or a hundred times that amount of data."

"No, no, no, no," Larry shook his head, a twinkle firmly in his eye. She was protesting far too much. "There's data, and there's hands on experience, these are two different beasts. That's why you have blackboards, and laboratories."

"You study the universe," Charlie pointed out, "and yet you've never been to outer space."

"Yeah, but if I had the opportunity, do you think for a moment that I'd hesitate?" The professor asked wistfully. There was silence for a moment, before he continued. "And anyway, it would give you more time with your sniper instructor."

"What?" Charlie spluttered. "That's not an incentive!"

"Really?" Larry smiled knowingly. "I think it's more of an incentive than you're willing to admit."

"I don't know what you're talking about," Charlie muttered as she turned back to her pads, and Larry laughed before deciding to drop the subject.

-BD-

"The weight of the gun, the noise of the shot, the effect of the recoil, there's no way I have of understanding that, because I don't know what it is to shoot a gun!"

"Exactly! Which is why I brought him in to begin with!"

Ian watched as Don stormed out of the room, apparently unaware that the noise of the argument had carried out into the bull-pen. He was impressed that the professor had realised what she didn't know and was trying to understand sniping, though he was a little curious as to why Don refused to let her try her hand at shooting. After all, it wasn't like she wanted to learn hand-to-hand combat or knife-fighting. Shooting a rifle at a paper target with a proper instructor present was perfectly safe.

Mulling it over, Ian stepped into the room where Charlie was leaning against the white-board, arms folded across her chest and glaring at the floor. He allowed himself a smirk – she really was adorable when she was cross.

"Hey there, Professor," he greeted her, smirk still in place as she jumped a little. "Couldn't help overhearing. Nice to know you can admit your shortcomings."

"Yeah, well," Charlie blushed a little. "As Larry said, there's data and there's hands-on experience. If I want to fully understand the data, I need to have the experience. Only Don doesn't seem to see it that way." She sounded so put out that Ian chuckled.

"Quite right," Ian nodded as he stepped up close, invading her personal space again. Charlie looked up at him, seeming to consider something, then smiled sweetly. Immediately, Ian was on alert, knowing that something was coming.

"You think I could use the experience too, don't you?"

"Absolutely," he agreed warily. He had an idea of where this was headed.

"So… will you teach me how to shoot?"

"Hmm…" Ian narrowed his eyes at her. "Won't Don disapprove?"

Charlie leaned up to whisper in his ear, and Ian suppressed a shudder as her breath tickled his neck.

"Who says that Don needs to know everything?"

She pulled away, and her smirk was mirrored on him. She was right, Ian nodded. Don didn't need to know everything.

"Well then," he half-whispered, enjoying the effect that it seemed to have on Charlie. "I guess we're headed off to the rifle range."

-BD-

"You don't need to flinch, you know," Ian bit back a laugh. "It's the other end that's dangerous."

"I know that," Charlie rolled her eyes. "It's just… I don't like loud noises. They've always bothered me."

"Fair enough," Ian shrugged before kneeling behind her. "Here, adjust your grip a little. Like this." He re-positioned her hand on the rifle, letting his touch linger a little. "Now try again."

There was something oddly calming about the way Ian was knelt behind her, Charlie thought to herself. It was as if he was waiting, ready to catch her if she jumped again. She let out a breath, drawing on the calmness, and fired. This time, at least, she hit the target.

"Good," Ian whispered, his mouth right next to her ear. "Reload and try again." His left hand was resting on her leg, and Charlie swallowed hard before speaking.

"Are we here to shoot or flirt?" She hated how husky her voice was, though Ian didn't seem to mind.

"We can't do both?" He asked, a smirk evident in his voice.

Charlie turned to look at him, then leaned forward and pressed her lips to his. She pulled away after a moment and gave him a smirk of her own, before giving her attention back to the gun.

"One thing at a time," she whispered.

"Fair enough," Ian agreed, and went back to teaching. Though now, he kept his arms wrapped around her waist. It was clear that he wasn't letting go any time soon.

-BD-

The next morning, Alan looked up in surprise as his daughter let herself into the house. He was in the middle of making breakfast, having thought that she was asleep upstairs.

"Morning, Dad," Charlie grinned at him, and Alan couldn't help feeling a little optimistic. Her lips were swollen, clothes more rumpled than usual, hair mussed, and a dopey grin was firmly on her face.

"You had sex," he commented, then waited as Charlie choked on her orange juice.

"Dad!" She spluttered. "What sort of a thing is that to say to your daughter?"

"A true statement," Alan said matter-of-factly. "You did. So, am I going to have a son-in-law any time soon?"

"I doubt it," Charlie said wryly. "He's… not the sort to settle down."

"Oh. So he's practise?"

"Dad!"

"What?" Alan asked, hiding a grin. Charlie looked mortified.

"I am not discussing my sex life with you. Just… no." With that, she turned and ran up the stairs to shower and escape her father's embarrassing questions.

-BD-

A few days later, it was all over. Charlie stood outside the hotel Edgerton had been staying at. She'd been thinking about what to say to him, but still wasn't sure. She sighed and leaned against his truck, waiting. After a while, the sniper himself appeared, bag in hand. He stopped in front of her and dropped the bag to the ground. He waited for her to initiate the conversation.

"Back to Quantico?" Charlie asked softly, and Ian nodded.

"I got classes to teach. Jobs to do. You know how it is." He sounded a little reluctant, and Charlie smiled. Sure, they'd agreed that it was a one-off fling, but maybe… maybe he did care.

"Well," she squared her shoulders and looked up at him, still smiling, "if you're ever in town again, swing by the house. You're welcome any time."

Edgerton looked a little surprised, then smiled back.

"I'll hold you to that. And if you're ever near Quantico, look me up." He handed her a card with his personal details on it, which Charlie pocketed.

"Will do," she nodded, then relaxed as he wrapped his arms around her and claimed a goodbye kiss. Before they could get carried away, he reluctantly released her, and Charlie turned to head back home.

It was better this way, she told herself. It was like she'd told Alan – he wasn't the sort to settle down with a family.

Now if she could just get her heart to accept it.

-BD-

Ian hummed along with the radio on the drive back home. He was already planning for the next time he would see his lovely professor. After all, it wasn't every day that he found a woman who he could argue heatedly with one minute, and have amazing sex with the next.

If anyone could convince him to settle down… he had a feeling it would be Professor Charlotte Eppes.

As long as he could convince Don not to shoot him for it.

-BD-

A/N: For the record, the votes currently stand at four each for CC and CE. It's going to be interesting seeing who likes where this is headed.