His joints ache. That's the biggest warning sign that he's been on Krypton for too long. Every time he moves, he's sore, and it makes him irritable. Which, okay, he's already pissed and scared and humiliated by everything that's happened in the last few weeks, but the joints don't help.

It had been rough enough to land on Krypton and discover that literally everyone is painfully beautiful. It's like he wandered into a dystopian, sci-fi version of Hollywood. And really, he should have seen that coming, since Superman and Supergirl both are some of Earth's most beautiful people, but it still was a shock to his systems.

Seg-El is the worst offender, because he looks like every male model Adam has ever pretended to not be attracted to. Wide, pretty mouth, pouty lips, a cheekbone that could cut glass, and a moody, thousand-yard stare: the man looks like everything that Adam has ever wanted and been too afraid to have, and of course, he can't have Seg, either. Not because of the species thing, or the time travel thing, or even the fact that Adam isn't exactly anatomically standard himself.

No, he can't have Seg because he's a liar, and Seg knows it.

He swings from irritation to angst — another sign that he should just go home — in a heartbeat. His chest aches at the memory of Seg telling him to just go home, how hurt Seg was that he'd lied to him. How Seg doesn't understand the higher loyalty Adam has, to Superman, to the integrity of the timeline.

And he believes in that, still. He has to. For Superman's sake.

Superman has to be his priority, because Superman has saved the universe. Arguably every life that will ever be owes itself to Superman, in the future that Adam knows

In the great cosmic balance, a few billion lives is a cost payable.

No matter what General Zod believes, no matter how much it hurts to ensure those lives' destruction.

Seg will survive. Lyta will survive. Kandor, technically, will survive, within the scope of Brainiac's collection. He can't assure anything else, and shouldn't want to, shouldn't try.

It's a choice he has to make.

Heroes make hard choices, and this is going to define him as a hero. Going toe-to-toe with General Zod to keep Superman from vanishing from history.

That's something he can't bear. That is what drives him on, as he makes for the city, rebreather strapped to his mouth, thermal clothes not keeping him warm but keeping him from dying of exposure. The Zeta-Beam sits in his pocket, his ticket home when this is all over.

He'll kill Dru-Zod. Somehow. And Superman will live.

He'll go home to the present, the future, and hopefully, not much will have changed. Superman will still exist, and that's what he wants to accomplish.

Doubt tries to creep in: if he kills Zod, Lyta's future might change. Would she even have children, if she has to see the end of her son's life? Might Seg keep from having a son, just to spite him and the future he's trying to protect?

Is it impossible to save Superman, now?

He pushes the thought away, arms wrapped tightly around himself. No. He can't accept that possibility. There needs to be a Superman.

Who knows who he would be without him, after all?

He'd been in his junior year of undergrad when Superman first appeared, and the world had changed. Humanity wasn't alone in the universe. Life spread out among the stars, not just on the planet.

For the first time, Adam found his attention turned outward, toward the future, instead of to the past. He changed majors — he'd been an archaeology major, then changed to astrophysics, adding a year to his degree. He'd chased the stars, became known for his grad-school work.

He'd met the Justice League when he was twenty-four. By twenty-seven, he'd gotten his PhD, consulted with the League on an alien invasion, and now, at twenty-nine, he's got the Zeta-Beam and a mission.

Save Superman. Protect the timeline from Zod.

He's got to do it.

Superman is too important, too much of an icon, a moral center for a decaying age, and he can't bear the thought of him ceasing to exist.

"Damnit, Big Blue," he whispers into the icy tundra.

He summons an image of Superman in his mind's eye: his cheekbone cut like Seg-El's, his eyes bright blue, his strong jaw and broad shoulders enough to bear the world on his back in metaphor and reality.

It'd been impossible to string a coherent sentence together in his presence, the first time they'd met. Even when he'd learned Kal-El was only a few years older than he was, that hadn't helped.

Superman was just too goddamn beautiful, and too goddamn good.

"You know, those are pretty bad for you."

Adam jumps a little, shaken out of his thoughts. Waiting outside the Hall of Justice for someone to come get him, he'd sunken into calculations for exploratory missions only possible for super-powered individuals, and lit up a cigarette just to have something to do with his hands.

He looks up, and shit, it's Superman.

He sputters a little. "Uh — yeah, um. I know."

Superman smiles at him. "You're Adam, right? The research astrophysicist?"

"Y-yeah."

He's starstruck beyond words, and his face heats. Superman, beyond being an icon of truth and justice, is gorgeous up close, beautiful in real life in a way that pictures just can't capture.

"Pleasure to meet you." Superman extends his hand for a handshake.

When Adam finds his hand in Superman's, well…

Game over.

He's in love.

Of course, Superman doesn't know. Or maybe he does. Adam still will never do anything about it — everyone knows about Superman and Lois Lane, after all.

All he can do is make sure Superman exists.

He thinks of the cape in the Fortress, left there when he left, its ragged edges emblematic of why he left Earth in the first place.

Superman needs to exist. The universe needs him.

Adam needs him.

He makes it to Kandor, stumbling into the city. The climate-controlled warmth hits him like a brick to the face, and he tenses, every joint in his body screaming in pain. He staggers to the side, leaning against a wall.

And fuck, he really needs to get home.

He hadn't expected to be gone so long. Heroes wrapped up shit like this in days, not weeks, after all.

He swallows. Three weeks without T is a long time, when he's been on it nearly fifteen years without a gap. He's getting paranoid, his hand rubbing now and then at the area on his thigh where he injects.

And it's not like he can get any on a foreign planet, after all.

He moves through the Rankless part of the city, realizing that it's too quiet, too empty.

Something's wrong, and he can feel it in his gut. He just hopes he's not too late.

Though, too late for what, he isn't sure.