Title: Reticence

Summary: Charlie fails to grasp the concept.

Disclaimer: Numb3rs does not belong to me. *despair*

1 Voluble

They're on the roof of a ten-story building, working the case of what looks like a jumper.

"So, Mr. Simpson, you were the first on the scene?" Don asks of the superintendant, eyes shifting behind his sunglasses to take in the CSU wandering about, and David, Liz, and Charlie clustered near the edge of the roof.

"Don't know about that," comes the answer, and Don turns his gaze back to the large figure in front of him, eyes narrowing. "All I know is, I'm in my apartment, and I hear a scream and a car alarm going off, and I looked out to see what the hell was going on. I don't know if I was the first."

Don frowns slightly. "Your neighbor, Mrs. Stewart, said she came out right after the scream, and you were already on the stairs."

Simpson looks down at him, and it takes him just a fraction too long to answer. "She's a little hard of hearing."

"Oh yeah?" Don's voice is calm, leaving it up to Simpson how to take it. The other man says nothing, but his eyes are shifting all over the place, and Don hasn't gotten to where he is without attentiveness. "You realize, Mr. Simpson, that Kurt Astor may have witnessed the murder of a federal officer, which also happened near this building." The large man is getting restive, and Don knows how to press his advantage. "I wouldn't recommend keeping something from us – or trying to protect someone," he tries, searching for a reaction.

"I don't know what you mean. The guy jumped, didn't he? It's suicide." He's looking nervous, but then being questioned by the FBI does that to a lot of people.

Just at that moment, a CSI comes up to him. "Agent Eppes."

Don nods dismissal to Simpson and turns to the CSI, but watches from the corner of his eyes as Simpson wanders over the group by the edge. He listens to the CSI, trying not to roll his eyes. Charlie keeps talking and expounding his theory, even while a possible key witness is standing there listening. Not only that, he's got David and Liz so involved in it, they don't realize how close Simpson is.

The CSI leaves, and Don sighs and shakes his head, barely concealing a smile. Yes, Charlie is frustrating when he's off in his own world, talking a mile a minute, oblivious to everything except explaining the concept to his audience, but here he is on a crime scene explaining projectile motion off a rooftop to FBI agents and Don can't help but feel a sense of pride – damn, his brother is good.

"So you see, given the short length of the roof along this side and his large mass, even if he made a running start, he would've fallen onto the curb, and not onto the road."

"Not unless he was pushed," Liz finishes with dawning comprehension.

Charlie beams at her excitedly, but Don isn't really paying attention, because his brain is already pushing ahead, corralling the facts – Astor's height and size, the need for an overpowering force, Charlie's incontrovertible math – and assessing them against the statements he's heard, reaching the only possible, alarming conclusion.

Don is used to sensing danger – he is always on the alert. And so almost before he sees the bulky figure step forwards, he is already moving towards his brother, yelling at him to move away, reaching for his gun.

Charlie takes just a little too long to stop talking and start listening.

2 Blabbermouth

The next thing Charlie knows, he's becoming unnervingly intimate with both the edge of the roof and the strong albeit sweaty chokehold of Simpson's thick arm.

"I'll push, I swear I'll push him off if anyone comes a step closer."

"Alright, just relax," Don says, in that authoritative but soothing voice he always uses with the more insane of criminals. Like putting a fidgety kid to bed, Charlie thinks, and resists the urge to giggle. "No one's going to get hurt here today. We're all walking away alive."

"Then put your gun down!" Simpson says, fear and bravado tussling in his voice.

"You know I can't do that." One cautious step.

"Back off, or I'm pushing him off!" The arm around Charlie's neck tightens, pulling him backwards, even closer to the edge.

"Alright! Take it easy!" Don's voice has an edge of panic too, though maybe only Charlie can hear it. He steps back one pace. "No one's going to crowd you. Just – just let him go."

The panic is definitely there, and if Charlie hadn't been scared before, he is now, because while him being scared isn't something particularly new, Don being scared? Yeah.

So he starts panicking himself.

"Did you know," he stammers out, "the angle we're standing at, relative to the edge of the roof and to each other, if you push me off, the probability of you falling as well is higher than sixty percent? Newton's third law, action and reaction," he adds frenetically.

"Shut up!" Simpson nearly shrieks, and the arm tightens even more.

"For God's sake, Charlie, just be quiet!" Don echoes, a hint of pleading in his tone.

Charlie wants to comply, really he does, but his mouth yammers on. "Besides," he wheezes out against the pressure at the throat, "with the wind shear on a building this tall, and the velocity of the wind at this altitude, we could both fall right now, even if you didn't intend it." His mind is busy drawing diagrams detailing the forces acting on him and Simpson and the building and calculating the wind load, which is fine because apparently his mouth can go on without his brain. "And since you have a higher center of mass, it's much more likely –"

Simpson screams again, and suddenly he can't talk or breathe and his eyes feel like they're about to pop out, and damn this is a crappy way to die –

And suddenly he's falling – only forward and to the left, and the floor is blessedly close, nothing like a hundred feet down, and he's kneeling, head down, and Don is crouching over him, hands moving over his head, neck, back, as if to make sure he's okay. He can hear the scuffle between Simpson and David – who must have knocked him down from the side – and then the sound of cuffs closing with a metallic click.

Don's moved back a little, only one hand at his shoulder now. "You okay, buddy?" he asks, almost calm. Almost. "Talk to me. You're alright?"

Charlie only nods his head, gasping harshly. He doesn't know why, but suddenly he doesn't want to talk anymore, and that strikes him as hysterically funny.

3 Communicative

They're sitting near the koi pond after dinner, relishing the warm twilight.

"So, I saw on the news that the case is over," Alan begins.

"Yeah. Turns out the guy who pushed the witness off the roof also murdered the agent. Another case closed," he finishes, and leaves it at that because he has mastered the delicate art of selective disclosure.

"Good thing, too. You two look like you definitely need a rest."

"No kidding," Don chuckles, taking a swig of beer. Charlie nods in agreement, though the movement is a little lopsided, Charlie being just a little buzzed from his own – multiple – beers over the evening.

Alan smiles, a trace of fondness in his eyes as he looks over his boys. "Maybe the two of you should go for a hike in the mountains for a couple of days."

"No thanks," Charlie mutters. "After today, I'm not going anywhere higher than my own height without four ceilings and a wall surrounding me." He pauses, then frowns in concentration. "Four walls and a ceiling."

Alan halts mid-chuckle. "After today?" His eyes are sharp, going from Charlie to Don.

Don groans.

He reaches over and slaps the back of Charlie's head and that, miraculously, seems to clear it enough for him to realize the huge can of worms he just opened. Don allows himself a snigger at his brother's widening eyes and the realization of 'oh crap' so clearly expressed in them, before turning to Alan, who is moving from surprise, coasting past curiosity and comprehension, and settling into hitherto-unexplored territories of rage.

"And just when were you going to tell me that a hostage situation detailed on the news involved both my sons?"

Don sighs, hits Charlie again (because it's his damn fault for talking so much), and reluctantly gives his father a highly sterilized version of the events, emphasizing the ludicrousness and taking artistic license with Charlie's distance from the edge of the roof.

Apparently his censorship is too lax, because by the end of it, Alan is sitting with an elbow on the garden table, face hidden on his hand. Don's a little worried, until his dad raises his head, and Don can see the famous I can't believe I raised a son with so little sense look that he is so familiar with.

"For a math genius…" he mutters, then trails off, glancing at Charlie, whose mind has wandered off happily somewhere in the middle of the story.

"Yeah," Don agrees, grinning a little.

Alan sighs and gets up. "I'm going to bed. You guys tire me out." He moves toward the house, pauses, and looks over his shoulder. "Donnie, the next time I say that I want to know everything…"

"Remind you of this moment?"

"Yeah." He disappears into the house.

Don grins for a few more seconds, then knuckles Charlie's head.

"Hey!" Charlie complains, a little fuzzily. "What'd you do that for? He wasn't that mad."

"You're just lucky your stupidity overshadowed the danger in his mind. It's like you don't even know the meaning of reticence." Don pauses to take another drink of beer and ignores his brother's automatic 'I do too'. "You know what scares me? You have higher security clearance than I do. It's a wonder we haven't all been blown up."

Charlie punches him lightly on the arm. Don blocks it playfully. They settle into the quietness of the evening – for a moment.

"Well, you know what Larry would say: maybe we already have." He waves a hand vaguely, the beer he is nursing sloshing with the motion. "Parallel universes and non-linear time."

Don gives a bark of laughter.

Charlie really never knows when to shut up.