Based on Mike Cahill's Another Earth. You don't need to watch it to understand what's going on here, but I strongly recommend doing so anyway because it's one of the most gorgeous films I've ever seen.

But maybe you should at least check out the trailer first! You know, to get in the mood. It can be found at http : / / youtu. be / N8hEwMMDtFY (remove spaces)

Done? Okay, on to the fic!

Fandom(s): The Big Bang Theory / Another Earth

Title: your fonder heart, half-lit in the half-light (1/2)

Ship(s): Sheldon/Penny, Sheldon/Amy

Rating/Warnings: T / spoilers for 5.10 "The Flaming Spittoon Acquisition"

Word Count: 3, 542

Summary: What would you do if you met the other you? In which there is a free ticket to space and a fine line between what is and what should have been.

chapter one: could have had it all (better luck next time)

It's been a year since the Tallis broadcast. A little longer than that since Penny caught her first glimpse of the other Earth, in the sky above Sheldon's shoulder. Roughly two since Sheldon Homo sapiensed up (down?) and asked Amy to be his girlfriend.

Not that Penny's, like, counting or anything. They're her friends so it's important she keeps their milestones in mind. And if sometimes she looks at them and wonders when the hell they'll finally break up, it's only because she still can't wrap her brain around the fact that anyone's willing enough to be in an actual relationship. With Sheldon Cooper. And vice versa.

She brings it up with the guys on occasion, the impossibility of it all. But ever since First Contact, they'd all been more relaxed about what was possible and what wasn't.

"Hey, if there's a whole other Earth up there, exactly like ours, with the exact same people in it," Howard or Leonard would tell her, gesturing to the ceiling, "that blows everything we know out of the water. I totally buy Sheldon growing a heart."

And it's strange, how Penny's gotten used to seeing a mirror image of her planet on the horizon but still finds it surreal when Sheldon and Amy go on dates. With touching and everything. It's strange how she's the only one.

Now they're all crowded around the television set in 4A, just like they were a year ago. Fireworks explode onscreen; the SETI Institute is celebrating the anniversary of First Contact, the day its director heard her own voice speaking to her over the transmission waves. The guys are once again embroiled in a heated discussion about how this proves quantum entanglement once and for all, while Amy and Bernadette nod. Penny gave up at quantum, but that's okay because the intensity of the conversation means she's got the champagne all to herself- or, at least, what little champagne Raj hasn't polished off.

And then Sheldon suddenly asks her, point-blank, "What do you think, Penny?"

That's when it all goes to shit. Sheldon-without-Amy would never have asked for her opinion on matters of science. Sheldon-without-Amy would never have made this, the latest in a long line of awkward overtures to move them out of the small-talk zone, to regain the balance they'd lost since an official girlfriend had been introduced into the fold.

Beside him, Amy kind of freezes up on the couch, eyes narrowing just the slightest bit. He's Sheldon-with-Amy who cares about Penny, and that somehow makes things way more complicated than they have any right to be, and Penny's a good friend, damn it, and she's buzzed and there's really no good time to tell them so she may as well tell them now-

"I won the contest," she says. "I'm going."

This is how Penny sees Earth 2 for the first time:

She's clattering down the stairs, Sheldon hot on her heels, chastising her about failing to drive him to his date with Amy last night. Penny grits her teeth against the killer headache. Of all the mornings to run out of coffee.

"Sweetie, I was drunk," she explains yet again. "I wouldn't have managed to get in the car, much less drive."

"That is immaterial," he snaps. Texas has crept back into his voice, pitched with anger. "We had an agreement. You were perfectly aware that you would be chauffeuring me to my destination at 6:30 P.M. Despite this prior knowledge, you chose not to abstain from your typical debauchery, and, as a consequence, I was unable to keep my engagement. Penny, that was the height of irresponsibility, even for someone such as yourself-"

"I'm not your fucking chauffeur!" she screams as she bursts through the doors. She whirls around to face him, hungover and so not in the mood to hear words like engagement come out of his lips, not when she'd barricaded herself in her apartment last night and downed Jack Daniels while he'd knocked and knocked and knocked and- "Jesus Christ, Sheldon, I am not-"

And there it is, hovering in the clear sky behind him. Bigger than the moon, although only slightly less silvery, with its swirls of white and blue and green. Her eyes widen. The rest of her sentence dies in her throat.

He turns around to see what she's looking at. She hears an intake of breath, although it's quickly stifled, like all his other displays of emotion are. She watches the heavens, his lean back and sharp shoulders still in her view. And she'll never be able to separate him from this moment. She'll never be able to erase this image from her mind. She'll never forget the silence and the early morning light, how they enfold Sheldon Cooper as he gazes up at another Earth.

After the initial shock of Penny's announcement fades, Bernadette hugs her, all happiness and excited squeals and warmth. Amy smiles, tight-lipped but genuine. Leonard, Howard, and Raj sputter congratulations and berate her good-naturedly for not telling them she'd joined in the first place.

Sheldon doesn't move a muscle from his spot, although she can see his knuckles whitening around his virgin Cuba Libre. "You are, I presume, cognizant of the perils of interstellar travel," he says.

"Well, we do have to attend training sessions-" she begins.

He cuts her off. "All the training in the world will be of negligible assistance if the ship were to encounter technical difficulties. I must categorically state that I have no faith in the spaceworthiness of United Space Ventures' Saturn V rocket model; they are a commercial civilian outfit, after all."

Leonard sighs, rubs the bridge of his nose. "Hey, Sheldon, are you by any chance familiar with the term 'wet blanket'?" he asks. "Because, right now, you're dripping on the floor."

"Forget dripping," mutters Howard. "This is a regular Noah's Flood."

Sheldon ignores them. He speaks only to Penny, but his eyes don't quite meet hers, focusing instead on a point by her right ear. "If the ship were to founder, and you were to die-"

"For God's sake, man!" Raj yells.

"- if you were to die," Sheldon persists, "your body would burn up on reentry, or remain lost in space. How, then, will we bury you?"

Penny recognizes this unforgivable brusqueness for what it is. He is concerned. That great big mind of his is reviewing all possible outcomes and what to do in case of the least desirable one. He will observe the proper rites, and he will do everything in his power to inject what order he can into a universe that he found out long ago he cannot control.

In the time before, Penny would have let herself be moved by this.

But the tension in the room is palpable and Amy's strung tighter than a harp string and life can never be sweet or easy and what's the other me doing now?

So Penny tilts her head, forcibly catching Sheldon's gaze in hers. There is only the two of them and the sound of the forgotten television and the slow bob of his Adam's apple.

"Don't worry about me," she tells him, in the most deliberate tone she can muster. He has another girl in his life to worry about, now. "I don't mind going out with a bang."

And it's true. Anything to be more than Penny. Anything to be more than a washed-up actress in a dead-end waitressing job. Anything to be more than a girl in love with her friend's boyfriend. She will be fine. She will soar into the stratosphere. She will get her ass killed, if need be. She will give herself up to the stars and the fire.

This is how Sheldon drafts the Relationship Agreement: he invades Penny's apartment and asks her what girlfriends do.

"Oh, I don't know, sweetie…" she murmurs over the rim of her wine glass. "What did your mom do for your dad?"

"Penny, the dynamic my parents shared was a far cry from an illustrious example of a healthy and functional relationship."

"Right, and a document that needs to be notarized isn't."

"Sarcasm?"

"You're improving." She stretches, her shirt riding up over her abdomen. His eyes trail on the exposed skin and she hastily slumps back down to cover up. Stories would have neater endings if the hero didn't peek all the damn time.

"Well," she says, drawing out the syllable, thinking back on the guys she's loved. Or thought she loved, anyway. "Your girlfriend is there for you when you need her. She helps you."

His pen scratches furiously across the clipboard. "Like drive me to work or to the comic book store when Leonard is being an appalling and unreliable mess of a human being?"

She almost chokes on her wine. "Um- yeah. And she understands you. She knows how you like things."

"For example, my food preferences and the importance of my spot?"

"Got it in one."

He nods, continues writing. His fingers are long and slender and there's something about the way they curl that makes Penny feel, all of a sudden, very alone. So because of that, maybe, there's a hint of wistfulness when she speaks again.

"And even if you guys fight and annoy each other a lot, you always work things out in the end because you want to stay together. She sticks with you no matter how weird you get. She takes care of you when you're sick-"

"Does she sing Soft Kitty?" The pen has stilled in midair.

Penny has to suppress the urge to close her eyes. "Only if you want her to, sweetie."

Sheldon frowns at his notes. In the ensuing silence, Penny's heart caves in with dread. She almost expects him to remark, all brilliant and smart-alecky, something along the lines of how You know, it occurs to me that these social conventions are insert-big-words-meaning-similar to the things you insert-big-words-meaning-do for me exclamation point. And then she would snort and banter and dodge and parry and breathe away the sharpness digging into her chest.

But perhaps even Sheldon Cooper is not that dense. Or that cruel. He stands up. He thanks her for her time. He leaves her apartment.

"You drink too much," Raj tells her, sooty and slurred.

She blinks. "That's rich, coming from you."

There's a six-pack from the convenience store at her side and there's Raj sitting on the curb outside her apartment building, flushed face turned to the night sky, to the other Earth that hangs in it. He'd obviously gotten sloshed in 4A and clambered out for a bit of fresh air.

"Do you think," he says, "that the other me can talk to women?"

It's the way he sounds. Distant, but also kind of sad. It makes Penny want to open a bottle of beer right here, right now.

"Do you want me to find out?" she asks gently.

He looks up at the constellations. All the stars he's known and mapped, now sharing the space above with this new satellite that hadn't been his for as long.

"No," he replies at last, shaking his head. "I won't be able to take it either way. Don't tell me anything. I'm not ready."

Penny shrugs. "Okay."

Howard is less shy about his dreams.

"Maybe the other me isn't Jewish," he gushes excitedly over Thai takeout. "Maybe the other me has a personal harem- with the other Bernadette as chief concubine, of course…"

"Unlikely," counters Sheldon. "Calculations would suggest that Earth 2 has been identical to ours in every possible way- until the point of discovery, when we learned of each other's existence, shattering the mirror. There is a new reality in place, which is still a reflection, however mangled and distorted, of the old original one. From that point onwards, our actions may have begun to deviate from those of our mirror selves in small ways, but certainly not to the extent that you are suggesting."

Penny furrows her brow. She's promised Amy and herself to stay away from Sheldon, and that includes not taking his bait, but curiosity's eating her up. "What about the whole many-universes thing?" she presses. "What about that one where you're made out of cotton candy?"

"I do not want to know, I do not want to know," Leonard chants under his breath.

"Earth 2 is not a parallel dimension, Penny. It is a mirror planet," Sheldon says. He pauses, giving her a fleeting, speculative look, chopsticks inches away from his mouth. "But I am pleased that you remembered."

She smiles at him. It's not her usual dazzling grin or her take-that-Sheldon smirk; it's soft but genuine, because even though she rather enjoys Amy and Bernadette's company she has missed these quiet moments when it's just her and her boys.

Perhaps Sheldon feels the same. He smiles back. It's twitchy and reticent, because Sheldon is twitchy and reticent in all possible dimensions, but it's still a mirror image of hers.

But before all that it's months ago and in the aftermath of the Fifth Great Prank War, Amy's standing ill-at-ease in Penny's apartment mumbling about the social impropriety of her boyfriend barging into another girl's bathroom with a fake knife, Psycho-style, while aforementioned girl's in the shower.

"I remain confident that Sheldon's feelings for you are strictly on the platonic level and that you would never betray me-" Swallow. Pause. And Penny's about to throw up because she's never in a million years expected to be having this conversation with Amy Farrah Fowler, and maybe it's all a sick joke, just another diabolical bazinga although Sheldon's already conceded defeat, but Amy continues speaking and oh God it's real, this is really happening- "While I respect that you and Sheldon have history as friends, surely it would not be viable to ignore the present for the sake of a remembered past. It is, in fact, emotionally unhealthy-"

Penny kind of wants to argue that Sheldon's never been emotionally healthy, wouldn't know emotionally healthy if it kicked him in the balls, but Amy's fists are clenched at her sides like she's prepared for a fight and even though her face is as unreadable as ever, there's a hint of entreaty in the way she sort of shies away from Penny's gaze.

Please understand, are the unspoken words that hang in the air. You are gorgeous and perfect and I've never been loved by anyone my whole life. I am your friend and I value you, but for all my talk about dismissing the past I am also still the teenager who spent Saturday nights at home. You are entropy, you are a supernova, you can draw anyone into your chaos. That's just what you do. I don't begrudge you that. But please just give me this once.

Penny imagines herself telling Amy, He was mine first. She imagines herself shouting that into the bespectacled girl's face. He was my friend before he was your boyfriend. I loved him first.

Instead, she takes a deep breath. "I'll tone it down," she promises Amy.

Unlike Sheldon, Penny has always known that she can't control the universe.

It's her last night in Pasadena. She's leaving for the Mojave Desert tomorrow for the training sessions. That's right; she's gonna train to be an astronaut. Take that, Omaha. Her face is plastered all over newspapers and television screens, lauded as one of those who won a free ticket to the other Earth. She's famous. It's not exactly like her girlhood dreams of stardom, but she's going to the stars, which is even better.

"To Penny," says Leonard, raising his glass and his voice over the music in the bar, "and to her first civilian space flight!"

"Civilian space flight!" she echoes, squealing. "That sounds so glamorous!"

"A common misconception," Sheldon snorts as the others clink their glasses together while he holds on to his can of Diet Coke for dear life. "In order to be a cosmonaut, one needs to undergo a rigorous fitness regimen and the unpleasant process of acclimatizing to zero gravity-"

She bares her teeth. "Shut up, Sheldon."

Amy and Bernadette are nowhere to be found. Penny would have liked to see them at her farewell bash, but they're holed up in their respective labs. It's just Penny and the boys, and there's this niggling thought at the back of her mind that this is the way it should be. At the beginning, she'd only had Sheldon, Leonard, Howard, and Raj. Now, here, at the end of her old life, it feels right that they're the ones she's saying goodbye to. Full circle. 360 degrees.

Well, look at that, she's learned a thing or two from these geeks after all.

"What did you write?" Howard asks. "In your winning essay?"

She squirms. She'd poured her soul out onto the keyboard, all of it, even the dregs. It's too personal, too much hers to share with anybody else. "The usual." She shrugs, breezy and unaffected. "I wanted to see what's out there. I wanted to matter. You know- the kind of corny stuff people usually write for contests like that."

"I beg to differ," says Sheldon.

Penny bites her tongue and she's seconds away from snapping at him because goddamnit, Sheldon, why do you have to make everything so difficult-

"Nothing about you is usual," he says, so quiet and low that she almost mistakes it for the music pumping through the speakers.

And, no, that's unfair. He doesn't get to do this. Not after all the pranks and the silly fights and the little moments and the car rides and him choosing Amy anyway-

Penny takes a swig of tequila.

And another.

And another.

And another.

In the essay she wrote, there's a part that goes something like:

When I was nineteen years old, I ran away from Nebraska to chase after a dream. Instead, I crashed into real life. There's a whole history there, about mopping floors and flirting for tips so I could pay the bills and putting up with asshole boyfriends one after the other.

Then one morning I looked at the sky and saw another Earth, and I thought about how much of the universe I hadn't seen, and I thought about my laundry and last week's failed audition and cheap tasteless dinners and hanging out at my neighbors' place because I had nowhere else to go.

And I thought: not this.

Her head's a mess and she gasps in night air. The alley wall scrapes her palms and the liquor's burning down nerve endings she's never even known she has.

"A hangover would be an auspicious beginning to your interstellar career." There's a beat, a snooty pause, and then, "That was sarcasm, by the way."

"You're really getting the hang of it," she snipes. She wonders why he followed her outside. She wonders many things as Earth 2 gleams in the black above his head. The bar's lurid neon sign sends slices of light into his ocean eyes.

Do you love me, up there? she wants to ask him. Do you love me, on the other Earth?

But in the end she goes with, "If you met yourself- Sheldon 2.0, I mean- and I'm still not over the fact that there's two of you running around, that's a pretty scary idea-" She falters. She's rambling. "Anyway, what would you say to the other you?"

He regards her quietly. She can practically see the wheels turning in his brain. She's expecting some long-winded answer about physics bla bla bla Nobel Prize, but, instead-

"What are you going to say, Penny?"

"To me?" She shrugs. "Maybe just… better luck next time."

And later they're standing outside her door, just the two of them because an inebriated Leonard's accompanied some smoky-eyed artist type back to her place- and, seriously, Leonard, picking up chicks at your ex-girlfriend's farewell party, stay classy-

Penny fishes out her keys from her purse and works it into the lock. The door swings open.

"Well." She looks up at Sheldon. "I guess this is goodbye."

He nods.

"I bet you'll miss me," she tries to joke, but it falls as flat as a chord plucked on an out-of-tune guitar string.

"Lately-" His voice wavers. He swallows, and tries again. "Lately there has been an alteration in the way you treat me, coinciding with the shift in mine and Amy's paradigm. Lately, I find that I am always missing you, even when you're around."

Penny did not ask for this. She did not ask for Sheldon to finally get a clue, here at the end of all things. She did not ask for this endless wanting, this all-consuming need to reach out and close the space between them. She has only ever asked for grace, all her life.

"Good night, Sheldon," she says, stepping into her apartment.

For a moment she thinks there's something like heartbreak on his face, but by then she's already closing the door, blocking him from view.