a/n Hello and welcome to a new story! This diverges from canon half way through S4, with the biggest twist happening at the end of S4. Be prepared for plenty of Bellarke angst, and plenty of Bellarke fluff, and all other good things. Happy reading!

With huge thanks to Stormkpr, who is the greatest beta a penguin could ask for.

Prologue: Before Praimfaiya

It's the stupidest thing, but it's a twisted ankle that makes the difference. A twisted ankle and a twist of fate.

Well, the twist of fate comes first, really.

…...

The sun is shining, as it will not shine much longer, glittering on the water, glancing off her hair. He sort of wants to tell her she looks beautiful, but the world is ending, so he's not sure it's quite the right moment for that.

"What will you do now, Bellamy?" Her voice, pitched low and gentle, washes over him. "Will you go back to Arkadia, or look for your sister?"

He was going to, actually. He was going to do those things. But somehow, standing here, watching her watching the ocean, he cannot turn away from her now.

"I want to stick with you, Clarke. I know we don't need another guard on the island but – if I leave now, I'm worried I might not see you again."

She doesn't answer that in words, at least not right away. She simply closes the space between them, leans into his warmth a little. And he looks down at her, at the half smile playing about her lips despite the oncoming end of the Earth, and tells himself that he has made the right choice, that he will stick by her side until the end.

She has just opened her mouth, just inhaled to speak, to say, he hopes, that she is glad of his presence, when Roan's shout has her running to the truck to despair over the lost hydrazine.

He doesn't know it, yet, but he has just changed the world.

…...

He's pleased with his decision in the days that follow. Sticking by Clarke's side was the right thing to do, of course, in as much as he couldn't bear to be separated from her in the face of this particular oncoming storm, but it turns out that it's the right choice on a rather more logical level, too.

They might not need another guard here, but they sure as hell need Bellamy Blake.

He's rarely felt so necessary, so purposeful, in his twenty-three years of life, as he does now, while all those around him struggle with moral dilemma after moral dilemma, and as Clarke bears almost literally the weight of the world on her shoulders. He can't do anything much to help with making the nightblood, of course. He's a soldier who happens to be rather overqualified in the field of history, not a biochemist. But it seems that what the other occupants of this lab need, just now, is not help with making nightblood, but with keeping themselves and each other sane.

She comes to his room that night, but it is not how he dreamed it. She does not slip out of her nightclothes and tell him that she wants him to set her aflame before the world burns, does not glide a provocative index finger confidently down the length of his cheek.

She sits, instead, heavily and hopelessly, on the edge of his bed, and tells him that she doesn't know what to do.

"We need to test the nightblood. We have to. But there's no good way of doing that, is there, Bellamy?"

She pauses for a moment, gathers her wits, twists her fingers in the satin of the nightdress that is, it seems, staying very firmly in place.

"We need to test it on a person. And there's no good way of choosing that person."

"Clarke." He shuffles close to her side, wraps an arm about her. Ignores, very carefully, the contact with her skin, and the beauty of her body in this tantalisingly civilian garment. "You're right. There's no good choice. But think of all the people this could save."

"If it works."

"Yeah." He can't argue with that. "I know that you'll make the best choice, Clarke. Even if it's a difficult one. You always do."

…...

He was wrong. He was so, utterly, totally, heartbreakingly wrong, and it makes him hurt to see it.

She hasn't made the best choice. She has made the worst one. The worst possible choice.

He suspects no one else has seen it, suspects, too, that no one else knows her well enough to understand even if they had seen it. But he can see Abby's hand shaking as she goes to inject Emori. Can see Clarke taking the needle from her, and raising it towards her own arm.

He doesn't think. He doesn't have to think. He already knows, on some deep and unconscious level, that he cannot let her go through with this choice. That he cannot let her inject herself, cannot let Clarke Griffin be the human subject of this most unfair of trials.

She's strong, in so many ways, but on the physical front she's no match for him. It is the work of a heartbeat to twist the syringe from her grasp, to turn away from her and stick it in his own arm.

It will be the work of a lifetime to forget her roar of anger and of pain, to forget the crazed look in her eye as she smashes the radiation chamber to pieces. It will be the work of an eternity, he suspects, to forget the rage with which Murphy screams at both of them that he will never forgive them for this, for trying to put him and Emori through what they could, evidently, not go through themselves.

But he can cope with those things, and gladly so, if it means that she's still by his side.

…...

She doesn't forgive him, but she does understand. She understands, she tells him, because she knows now how he felt, watching her offer herself up for that fate, from her own experience of watching him and then falling apart far enough to smash up that radiation chamber. She is supposed to be the rational one, for goodness' sake, yet the events of that day were enough to send even her far beyond the reach of reason. So there was no hope, then, that he could have endured that situation without some kind of emotional overreaction.

Some kind of emotional overreaction like, for example, injecting himself instead.

The experience builds some kind of bond between them – not that they weren't already stuck together like glue – but it has made all too plain what was, previously, unseen and unspoken. That somehow, somewhere along the line, they have reached a place where they would willingly give their lives for one another.

Of course, with so much firmly established, Clarke then finds herself trying to decide between his life or the lives of the entire human race.

He knows that's how she's seeing it, as he stands atop this ladder en route to admitting his sister, knows that's the question she's asking herself, with her saving humanity hat on. But she doesn't seem to be finding her day job quite so easy, just now, he notes, as he watches her hand shake and sees her raise the gun reluctantly.

She won't shoot him. He knows it. He knows it about as well as he knows his own name.

"You'll have to make it a kill shot." He tells her, looking her right in the eyes. "That's the only way you're going to stop me."

She shakes her head, once, weakly, almost pathetically. She lowers the gun, turns away from him, and he can hear her trying to apologise past the sob stuck in her throat.

He needs to let his sister in, of course. And then he needs to extract a promise that Clarke will not be condemned for this, and then they need to get on with saving the human race.

But somehow, all of a sudden, quite before he has had the chance to decide whether he wishes to do so, he has crossed that cold concrete floor and enfolded Clarke in his arms. And she's crying, hard, and he's cradling her precious head to his chest and he knows, of course he does, that they haven't the time for this.

But how can he leave her now?

"I'm sorry." She hiccups eventually, tries to pull away, but he's not having that. She's not ready to face the world just yet, he can tell. "I just – I couldn't. Too many people I loved are dead because of me. I couldn't let it happen again."

His breath hitches at that, but not in a sob. In a gasp of disbelief that she should choose this moment, of all moments, to unleash the topic of love. But there are, of course, things to do, sisters to rescue, a world ending.

"I know. I couldn't have shot you either." He tells her, stroking her hair.

There is a pause. A second. A couple of muffled sobs.

"For the same reason." He murmurs, and then he gives in to his cowardice, and runs away to open the door.

…...

They don't talk about that moment, about those precious words that passed between them. They talk about boring things, logistics, how to get to the island. How to rescue Raven, how to get home in time. She tries to apologise once more, but he's not having it. The time he has left with her might well be too short, he suspects, to waste it on apologies.

He asks her instead about her childhood, as he tries to navigate this twists and turns of the track, bathed in the glowing orange of the oncoming death wave.

She looks at him, brow cocked, as if to ask why the hell he is interested in such trivialities at a time like this. But she does not argue, simply starts to tell him tales of Jake Griffin, and of centuries old football matches played out on a big screen, and he relaxes into the road ahead and the rhythm of her words.

He relaxes so much, he hits a tree.

It quickly becomes clear that the fault was not his, as a small army springs from the forest around them. It is a blur, all flying dust and spraying snow, eerily backlit by that distant fire, but he makes out enough to be afraid. Countless bodies, converging on them. Murphy and Emori surviving, as they do best.

Clarke taking a heavy fall, screaming as she goes down.

And then Echo rides to their rescue, thank goodness, and he wonders how it is that this frosty traitor is always showing up to save him when he needs it the most. He is so busy sagging with relief, and checking that everyone's suits are intact, that he almost does not notice that Clarke is still sprawled on the ground.

"You OK?" He asks her, confused to say the least. She's obviously conscious, but she's not getting up.

"Yeah. Except that – I hurt my ankle when I fell."

He kneels at her side, not sure what use any help of his could possibly be to this woman who is virtually a doctor.

"Is it broken?" He asks, cursing their luck. This day was going badly enough before she got injured.

"I don't think so." She flexes it experimentally. "Just twisted."

"Well, it's a good job we're stuck sitting here until Monty and Harper show up."

"Yeah." The ghost of a smile plays about her lips. "Yeah, it is."

…...

As it turns out, a twisted ankle does not prevent her from sitting in the front seat of the rover when it arrives and chatting to him about everything and nothing. It does not prevent her, either, from conceiving the plan that will save them all, and making a start on working out how they will get to space. Nor does it prevent her from sitting by Raven's side to work out the arrangements for water, or food supplies, of just about anything at all.

It will prevent her, though, from running to the satellite tower. On this point, his mind is made up.

"I'll go." She is, of course, the first to volunteer when Raven tells them that someone needs to run this riskiest of errands.

He would laugh, if it weren't so serious. She must realise, as she hops awkwardly to her feet, that there is no way she is hiking through the snow with a time limit.

"No." He insists, firmly, twisting the kit out of Raven's hands, much as he wrenched that syringe from Clarke those few short days ago. "You can't, not with that ankle. I'll go."

He turns away, is three paces into the journey towards the stairs when he hears her voice.

"Bellamy, no! Please!"

He wheels back around to face her, aware that he's looking at her like she's lost her mind.

"Clarke. You can't walk. I'm going, and that's final."

"Please." The tears are coursing down her cheeks, her whole body shaking as she limps pitifully towards him. "Please. I want to stick with you. If you leave now, I'm worried that I might not see you again."

She throws her arms around his neck, sagging into him as her injured ankle gives out, and he does not hesitate to hug her right back. It is not a long embrace, though, because he has things to do, and people he loves to keep alive.

He loosens his arms, and before he can think better of it, he presses a rather abrupt kiss to her mouth. And he can see it, as he pulls away, can see in the look in her eyes that she understands exactly what that kiss means. That she'll stick around and wait for him to get back, no matter what the end of the world may throw at her.

"May we meet again." She murmurs, clinging to his hand until the last possible moment as he turns to leave.

"We will meet again."

a/n Thanks for reading!