The time stone was all that remained. Technically this one came before his collection of the mind stone, since it happened before the battle was over. But there was a reason Steve was saving this one for last.
Time. Time confounded him, stretching sometimes and skipping others, the way seventy years had passed without a trace and how in fifteen years he'd hardly aged a day. Wrangling the vagaries of time was the mission he'd been tasked with.
He was so close. So close to having completed his charge and clipped all the branches. It was important to preserving their victory, to ensuring that they didn't damage the past in attempting to save their future. Just one more stop, and then he could—
What? What was there after this? There had always just waiting for the next crisis, or at best the calm before the next storm. There was never really an end for him, who had given himself over to always being the man that stepped up. Because he didn't know who he was, what he was good for, without it.
"What do you have to do, Steve?" Bucky had asked him. "How much do you have to give up and suffer through, before you get to be good enough?"
The question stopped him dead in his tracks. How could he ever know, when there would always be more battles to fight? When the world would never stop needing, no matter how much he did?
"Somebody's got to do it," was all he could manage.
"So why's it always gotta be you?" Bucky shook his head. "Who died and made you Jesus?"
Steve had to laugh despite himself. That was the trouble, he supposed, of taking so much upon your own shoulders— you made yourself awfully important.
Bucky moved in close, laid a hand upon his shoulder. "Don't get me wrong, there's only one you, Steve. I've got no doubt about that. But… you're not the only superhero in the world anymore. Let somebody else carry the shield for a while."
Steve snorted; they'd gathered the broken pieces of vibranium from the battlefield where Thanos had left them. "There isn't even a shield to carry anymore."
"Great. Even easier."
Steve grinned crookedly and spread his hands. "Oh, yeah? You want to do this?"
Bucky barked a laugh. "Be Captain America? Not a chance in hell— I've seen what it's done to you. But… you've got good people now. Don't you have faith in them?"
Steve dipped his head, suddenly chastened. It was not fair to discount the enormous courage, integrity, and valor of the people he'd fought beside. They weren't only teammates or colleagues or even heroes; they had become his friends. After everything he'd given up to carry on as Captain America in the Twenty-First Century, they were the one thing he'd gained— their friendship, that family. The people without whom he never would have survived to keep picking himself back up.
Bucky's eyes regarded him so solemnly. "And we want you to be happy, Steve."
Steve looked at his best friend then, the one for whom he had fought and sacrificed, the one connection to his old life he'd managed to keep. "And what about you, Buck?"
He shook his head. "There's no undoing what's been done to me. I have a chance now, maybe, to… get past it. Move forward, someday. And that's all thanks to you. But the rest is up to me now; there's nothing more you can do. For you, though… maybe you can do something."
"Do you really think…" Steve swallowed hard; when he tried to speak again, his throat felt as if it had closed up. "Do you really think I could go back?"
Bucky leaned in close. "As long as I've known you, you've only ever wanted three things. You've taken care of me. And you've been doing right by the world for as long as I can remember. All that leaves… is her."
One last stop. It was the rooftop of the Sanctum Sanctorum of the Sorcerer Supreme, where Bruce had made his bargain to borrow the time stone on the condition it would be returned. Steve's last job was to hold up their end with the Ancient One, who was waiting for them to close the loop.
Steve wished he'd had the chance to ask Stephen Strange about her, but all he had to go on was Bruce's encounter. He'd told Steve about how she had been the one to teach him about the consequences to the timeline if they did not return the Infinity Stones to the points from which they'd been borrowed. Indeed, her knowledge of the workings of time was extraordinary; she even seemed to know of Strange's eventual coming, several years before any sign. All of this Bruce had learned once she'd knocked his soul straight out of his Hulk body, only to return it once she was done.
"She's got serious power," Bruce said. "I've never seen anything like it."
She was of course still on the rooftop on Bleecker Street, where his friend had last seen her, doing her part in the battle of New York. Though Steve had never laid eyes on her himself, her presence was unmistakeable. She was a tall, lean figure with sharp features and a smooth bald head, swathed in a brilliant yellow sorcerer's robe. Around her neck she wore the same eye-shaped amulet that Strange did, an heirloom passed down to him from her. As Steve appeared on the sanctuary rooftop, she was conjuring circular grids of golden magic from her hands, blasting the alien warriors and shielding the surrounding buildings from their attacks.
"Excuse me," he called, causing her to turn. "I think I have something that belongs to you."
She looked him up and down in a way that, like Queen Frigga, made him feel as if she saw right through him. She tossed out a burst of power over her shoulder, nailing a Chitauri flyer without even a glance, and smiled.
He approached. "Forgive me. I don't mean to interrupt."
"Not at all, Captain Rogers. I've been expecting you." She chuckled. "Well, not precisely you, but… Dr. Banner promised me someone would come." She tilted her head curiously. "I take it your gambit worked? You succeeded?"
"Yes," he answered solemnly. "Though not without cost."
She nodded. "Of course. There's always a cost."
Steve knelt to open the case. She tensed her fingers and swept them past each other in front of her chest, making her amulet open and glow. The time stone rose from the case and floated toward her, winking with green light until the amulet closed around it, sealing it back inside.
There it was. That was it, the sixth and final stone returned to its proper place. His mission was complete.
He dropped his gaze from the amulet to stare down into the empty case. He should have felt relieved, like his burden was lifted. But all it meant was there were no more distractions, nothing else to pursue. All that remained was his own struggle, the one he'd been wrestling with since his last conversation with Bucky.
After a moment he shut the case and rose. The Ancient One nodded to him, satisfied. "Thank you, Captain."
But he made no move, only stood there, case in hand. She raised her chin slightly, regarding him. "Is there something else?"
He was silent for a beat. "You've done this for a long time," he said at last. "Haven't you?"
She smiled, as if he couldn't know how true that was. "I have."
"Could I ask you something?"
She nodded, expression curious.
He swallowed. "How does it work? When you go back and time, and take action that changes things. How does that work?"
"For most such actions, it doesn't." Her fingers flicked in an arcane gesture, and the golden threads of her magic coalesced into a flowing continuum. "The timestream is not fragile— the free will inherent in the choices of all living beings is not easily subverted. But in the absence of cosmic forces like the Infinity Stones, most of our deeds will not change the course of the whole world."
Steve watched as she sent ripples through the river of light, that pulled the stream this way and that before settling in along on its forward course.
"And what if something else changes?" he asked. "Something smaller scale than an Infinity Stone, but that still managed to have consequences on the world."
She folded her hands into the sleeves of her robe. "Did you have something particular in mind, Captain?"
Steve drew in a deep breath. "Bruce said you could… see things through time. Do you know where I came from? Not just now, but before?"
"You mean, the ice in the Arctic of 2011?" she asked. "Where you crashed down in an airship in 1945?"
He nodded, and bit his lip. He cast about for some way to say it, to ask without asking her the question that had been twisting in him. It seemed so wrong, so impossible a wish. But he had crossed the universe, tangled with the timestream, lived as something more than normal man, and now he was staring down a mistress of power inconceivable. The impossible was all that was left to him. In that moment, all pretense fell away, and he told her what he was carrying in his heart.
"There was a woman then," he said softly, gaze downcast. "Before I went into the ice. We were— we had something. But then came that mission, and I thought I would die… but I didn't. I woke up, seventy years into the future. And then everything I had was gone."
He sighed again, to steel himself. "I thought I could… move forward. That our time, our chance, was past. But I could never get her out of my head. And now… that time doesn't seem so fixed anymore."
He looked up to meet the Ancient One's eyes. She regarded him in new understanding. "You want to go back."
"I want to," he breathed, and the enormity of speaking it, confessing it aloud for the first time, almost crushed him to the floor. "I don't think I can go on much longer with the life I've been living. And once I had hoped once to have a life with her. It occurred to me that, now… maybe we have that chance after all."
The Ancient One listened to his story intently. "I see."
Her gaze on him was piercing; he had to pace away. "But… she already had a life. Children, with another man. I carried her in a box at her funeral. She picked up and moved on, did and accomplished so much that had nothing to do with me."
Finally he stopped, nervous energy exhausted, and raked a hand through his hair. "I can't just… erase all that. I can't erase them."
He tuned back to the Ancient One, eyes pleading. "Is there any other way? Do I have any hope?"
She was silent a long moment, looking at him very seriously. "Will you come with me?"
He nodded. Brilliance exploded from her fingertips, and the whole world around them changed.
His sight was dazzled at first, such that he could not see what was happening. But when at last it cleared, Steve let out a soundless gasp. She had transported him somewhere, to a realm of brilliant threads of color and texture indescribable, weaving in and out of each other through the darkness. They twisted and surged through the darkness, knitting themselves into a pattern of complexity beyond his comprehension.
For what felt like an age, Steve could only gape. He felt adrift in the sea of it, as if it would swallow him completely. He tried to ground himself in his body, but there was no gravity, no sense of up or down. In his wonder he caught sight of his spreading hands, and was surprised they were not the large masculine paws of his super soldier body, but the fine-boned, knobby-knuckled fingers he'd grown up with. Steve suddenly remembered Bruce telling him how the Ancient One had smacked his soul in human form out of his body; she had summoned Steve's true inner self too, in the shape of his skinny, asthmatic body he was born with.
"What is this?" he asked, somehow speaking without sound or words. Just the same, he heard without hearing the voice of Ancient One, who appeared beside him amid the churning threads. Her presence seemed huge to him now, especially at his frail, pre-serum stature.
"This is the timestream," she said. "The great tapestry woven of all the strands that make up the universe. Every agent, every actor, every force that drives our path, pulling and knotting with one another in the sum of all possibility. No one strand can change the course of all others, but all paths are the sum of all the strands they link with."
She sliced with her hands, and their perspective abruptly changed. Steve had difficulty focusing among the chaos, but the glow of the Ancient One's magic pulled his eye; amid the tangles he saw a— a shifting of some sort, where one thread was pulled and tugged on by another, as if it would break before turning on its way.
"The course of history runs strong. But when there are forces at play that can alter the path that time has taken, a new possibility unfurls beside it. Not a change or erasure of reality— but a new reality, split off with all the consequences of that choice."
He watched the strand, not break, but rather divide, pulling away a new strand, a forking like Frost's two paths through the yellow wood.
He gasped without his body breathing. Suddenly he recalled a term he thought he'd learned from Bruce. "A… a multiverse."
Possibility. Alternative. If he went back… he wouldn't erase Peggy's life here— just start another, different life. He could start himself another, different life. One he only just let himself dare to dream of.
Abrupt uncertainty gripped him then, and he turned back to the Ancient One. "Can you see what would happen? If I… started that branch?"
She shook her bald head. "In my work I have learned to read some things from the threads of time. But no mortal can comprehend enough to predict all possible futures."
"That makes sense," he conceded. "It's only… how could I ever justify it? When I can't know what might come of it?"
His vision filled with light again, and the vast crisscrossing map of time around them began to fade. He could hear the Ancient One laughing, making the very universe around them seem to shake. "But that's just it, Captain Rogers," she chided. "No one can everreally know what will come."
Steve thought of every desperate moment, every tight spot, every instance he'd been called upon to be a leader through an uncertain time. How he'd had to make decisions as best he could, to do the most he could, when there was nothing to guide him but his own moral compass, his own brain and gut and heart.
His eyes cleared, and he was once again on the rooftop on Bleecker Street, once again huge and towering in his super soldier body. He looked down to meet the eyes of the Ancient One, who was smiling at him in that knowing way.
"That is the risk you take," she said. "When you love."
Steve closed the fingers of the hand upon which he wore his GPS watch. Without words, he inclined his head, and she bowed her own in return.
Breathing deep to strengthen himself, Steve set his watch for one last jump.
