Disclaimer: The Avengers is owned by Marvel Entertainment and I am just borrowing the characters.
Author's Note:
Spoilers for Avengers Endgame. Don't read if you wish to remain unspoiled.
Pairings: Tony/Pepper, Steve/Peggy
Content warning for character deaths and grief.
Companion story to Think About You, Hope, Not For A Second, Made For This and A Good Man. All stories can be read as a stand alone or as part of a series.
Cross-posted to AO3.
One Last Time
"Don't do anything stupid until I get back."
"How can I? You're taking all the stupid with you."
o-O-o
The time jump lands Steve directly on Vormir just seconds after Clint departs.
Thanks to Natasha and Clint's visit they had better coordinates which they could use to set the Time-Space GPS and Steve is thankful he didn't need to travel through space to get to the planet.
Steve makes the long walk up the mountain. He's glad of the quantum suit. It keeps the cold out.
There's a buried hope in his heart that gets stronger with each step.
A soul for a soul.
Clint had described the exchange that Natasha had made to get the Soul stone and Steve hoped if they gave the stone back that maybe, maybe they could get Natasha back. She deserved to come back, deserved to see everyone returned from the snap the way she had so desperately wanted.
He makes it all the way up the mountain without seeing a single living creature.
"Steve Rogers, son of Sarah," the voice intones.
Steve turns around sharply. He'd thought himself ready to meet the guide but he's still surprised. He lets his heart slow and his breath even out before he responds to the shadowy figure. "You know me?"
The figure lifts its head and Steve's breath catches.
"I know you well, Captain Rogers," Red Skull states.
Steve readies himself to fight. He has no shield, but he has Mjolnir. "You're the reason why Natasha is dead?"
"I am only the guide," Red Skull counters. "I was sent here by the infinity stone years ago and cursed to stay in this place for all eternity to guide those who would seek the Soul stone." He looks at Steve with burning hatred. "If you had not interfered in my plan, I would have ruled the Earth instead of being banished to this desolate place."
"It's no more than you deserve," Steve counters angrily.
"Still so righteous," Red Skull mocks him. "Your morality and pure heart will make no difference to the Soul stone."
Steve grips Mjolnir hard. "You know what I'm here to do."
"You are returning the Soul stone," Red Skull says, "but it will not return to you what was given freely."
Steve swallows down his disappointment. "You're lying."
"It is an everlasting exchange," Red Skull states.
It's the same words Clint had used to describe the exchange, and Steve remembers how Bruce had talked about trying to bring Nat back with the snap of the infinity stones but he couldn't.
Steve firms his lips. He can try. He raises Mjolnir and points at Red Skull. "Bring her back!"
"Even if there were a way," Red Skull notes, "why would I tell you?"
Steve feels the anger rise in his chest; lightning crackles down his arm and over Mjolnir.
Red Skull smiles. "Do it," he taunts him, "do it! Strike me down, Captain America! Strike me down as you should have all those years ago!"
Steve breathes in deeply. He can't just strike down Red Skull. He knows that. The guide has to remain; the timeline has to be intact to snip off the branch that might emerge. He ignores Red Skull and steps around him to face the edge of the platform.
He looks down into the abyss.
There is nothing below him; no body lies on the ground.
He takes the Soul stone from the case and holds it out. Its amber light glows in the dark of the planet.
"Please," he whispers, "please send her back."
He drops the stone.
For a second nothing happens. But then there is a rumble of thunder. Blue light zig-zags up the mountain and…
Steve comes to lying in a puddle of water. He sits up. Mjolnir rests in one hand, the case in the other. The stone is gone. There is no-one else around him. Apart from the absence of the stone itself, it's just as Clint described it to Steve.
Steve calls out anyway. "Natasha!" He looks around him, whirling from side to side, trying to hope, trying to peer into each corner of darkness…
There is no-one.
Natasha hasn't been returned.
She's gone.
Truly gone.
Steve's legs give way underneath him and he's on his knees in the water, crying. Tears streaming down his face. He lets himself feel the pain of losing his friend, let's himself mourn for her in a way he hasn't since he'd returned to the time platform and realised she wasn't there.
He and Natasha…they've been keeping each other afloat for the last five years. She's been his confidante, his sounding board and his rock. He hopes he was the same for her.
He's going to miss her. But she'd made her choice and he has to respect that.
He swipes at his face. He picks up Mjolnir; puts the case under his arm and modifies the bracelet to the next coordinates. He looks out one last time to the mountain.
"Goodbye, Natasha," Steve whispers. He taps the bracelet and Vormir disappears.
o-O-o
Morag is another dark and gloomy place.
It suits Steve's mood.
He lands directly next Rhodey startling the hell out of War Machine who turns with guns automatically rising in response.
Steve holds up his hands, quickly. "It's me. I'm here to return the stones and snip the time branches."
"Say what?" asks Rhodey.
Steve shakes his head. He looks at Nebula. "You need to go back to the future now otherwise your father will know of our presence here."
Nebula blinks at him but she obediently taps her GPS and goes.
Rhodey stares at Steve. "What the hell…"
"Long story," Steve says. "I'm going to stay with you, you'll grab the stone, take it to the future. I'll replace it immediately."
Rhodey shakes his head. "Did we screw something up in the future?"
He sighs. "Bruce spoke to the Sorcerer Supreme; we have to snip the timeline branches at the moment we created them to ensure that the stones are back in our timeline past where they are meant to be so we don't create alternate timelines." He makes a vague gesture. "Quill has to find the Power stone and events have to play out as they did before."
"OK," Rhodey says, "but you just said that Thanos finds out Nebula is here so did something happen which you've now stopped?"
The question arrests Steve. For a second all he can think of is Tony; the image of Tony lying on the ground, dying, dead. Steve shakes his head.
Has he stopped Thanos from entering the future? Has he stopped the attack on Earth? Or has he just created a new timeline, different from his own where Tony doesn't die but everyone gets to come back? The way Bruce has described it, the timeline branch where Thanos makes the jump to the future will happen regardless of Steve's return to the past and any actions he takes.
Time travel.
It makes Steve's head hurt. He sighs. "Don't ask me to explain it."
Rhodey huffs but accepts it. The next few minutes happen the way Rhodey and Nebula had described to Steve; Quill arrives, Rhodey knocks him out just in front of the temple. They steal the lock-pick, enter the temple and with the use of some tongs extract the orb from its laser cage. Rhodey nods and departs with the stone.
Conversely, Steve knows he doesn't have a lot of time to get the stone back in place; Quill could recover at any moment. He takes out the original orb which had contained the stone and using the tongs he puts the Power stone back into it. He carefully places it back into its cage; the tongs heat up, glowing red as they slide through the bars.
Steve winces and is glad of the thick gloves he wears. Finally, it's done.
He makes his way back out of the temple. The doors are still open, and Steve uses his brute strength to close them again, happy when he hears the locks engage.
Steve checks on the unconscious Quill. He replaces the lock-pick exactly where they had taken it.
A noise above has Steve's head lifting to the sky.
Quill groans and Steve slides behind a rock.
He's squished behind a wall and he's not at all comfortable. He tries to reach to the GPS, but he hasn't got a lot of room to manoeuvre and when the small sound he makes draws Quill's attention, he immediately freezes.
Quill shakes his head and gets to his feet. A few minutes later he's entered the temple.
Steve reaches for the GPS but approaching footsteps have him freezing again. Three aliens approach.
He waits as they banter with Quill, as a fight breaks out.
They all disappear in the opposite direction to Steve and he breathes out.
He hurriedly sets his GPS. The Power stone is back in play in the timeline as it should be. It's time to move on.
o-O-o
Asgard takes his breath away.
After the darkness of Vormir and Morag, he's surprised by the golden beauty of Thor's home world. For a long moment he stands on the balcony where he's landed and looks out just overwhelmed. It's grand and grandiose; alien and wondrous. He can see why the memory of the place hurts Thor and can't quite believe that Thor was able to take the step he needed to destroy Asgard to save its people.
"Hello, Captain."
Steve whirls around and finds himself face to face with a beautiful dame. Her long red hair is braided into a fancy hair-do; her dress is silken and turquoise. She looks stunning and his artist's eye wishes for paints and a canvas so he can paint her.
"I am Frigga, Queen of Asgard," she says calmly, "and you are here to return the Aether to its rightful place in the timeline."
"Yes, ma'am," Steve responds, breathless at the idea that he's talking with Thor's Mom.
"I will help you," Frigga says. Her eyes sparkle with mirth in a way that reminds Steve of Thor. "But first we must do something about your outfit."
Her hand waves and his quantum suit turns into a set of armour not unlike Thor's. He has a blue cloak and blue leather pants; a chest-piece. His arms are bare, revealing his muscles.
"Much better," Frigga says with satisfaction. "Come with me."
She leads him through the palace and into a quiet room. There's a table set out with food and drink.
"Rest, replenish yourself," Frigga instructs him.
Steve hesitates, he just needs to get this done. "Ma'am…I mean, your Majesty…"
"Frigga," she stresses and directs him to a chair.
"Ma'am, Frigga, I don't really have time for this," Steve protests.
Frigga waves a hand and a golden bubble zips up around them. "And now you do."
Steve looks at her confused.
"We are in a mirror dimension where time moves differently; we can spend many hours here and only seconds will have passed in our own time," Frigga explains.
Steve wonders if this is similar to the quantum realm. He sits down and is suddenly grateful for the opportunity to rest.
He accepts the juice and the food Frigga presses upon him. "Thank you."
Frigga hums. "How is he?"
Steve's not surprised she's asking after her son. Thor had spoken with wonder about getting the opportunity to speak to her one last time.
"He's doing better," Steve says honestly. "He's given the throne to…"
"Valkyrie," Frigga supplies and smiles at his astonishment. "There are things a mother sees, and things which a witch just knows."
Steve swallows down the mouthful of sandwich, decides not to poke that sentence with a barge-pole, and nods. "He's decided to spend some time in space with some friends."
"The furry beast who was here with him?" Frigga asks before nodding herself. "He is a good choice. He understands what it is to lose everyone." Her eyes narrow on his. "As do you."
"I haven't lost everyone," Steve counters gently. He hasn't lost Bucky or Sam. He still has friends to go back to in the future.
"But there was a time when you thought yourself alone," Frigga says, "and for all you have, you continue to mourn what is lost; you dwell on what might have been and not what is."
Steve gives a short laugh at her insight. She has him pegged. "You're right; I can't seem to move on."
Frigga smiles at him. "You and my son are much alike," she says, "and not just because you are worthy of wielding Mjolnir," she nods at the hammer on the table, "you are both so focused on being who you think you are supposed to be that you have lost sight of who you are."
Steve feels the truth of her words.
"Perhaps you should also spend time discovering who Steve Rogers is," Frigga suggests.
"I don't think there is any time for me to do that," Steve says.
Frigga smiles again. "You have nothing but time at your disposal for the next little while, Captain," she points out, "you should use it wisely."
Steve rubs a hand over the back of his neck. "Maybe."
Frigga gestures to him. "Give me the Aether and I will return it to Jane." She raises a hand when he goes to argue. "You will be very out of place, Captain, in a ladies' room."
Steve blushes. He almost protests anyway, but he concedes handing over the stone and the injection device. "I have to admit, I'm not sure…"
Frigga does another gesture with her hand and the stone slides into a rolling mass of red and black. She quickly contains it within the injection device and nods at Steve.
"Rest, Captain," Frigga says, "this space will remain until my death."
Steve winces.
"Do not be sad," Frigga says, "I have lived thousands of years. I've known love and heartache; joy and sadness. I have my children; my husband. I have lived a full life."
Her words touch Steve. He'd given up the idea of that life, full of love and family, when he'd come out of the ice; he can remember telling Tony as much after Ultron. But he wants it…he still wants it very much.
Steve gets to his feet and bows his head. "It's been an honour to meet you."
"And it has been my honour to meet you, Captain." She reaches and picks up Mjolnir. "I believe my son may have need of this." She grins at Steve's surprise and leaves in a swirl of fabric.
Steve's clothing reverts to the quantum suit. He sits down heavily in the chair. He can't bring himself to eat anything more. He rubs his hands over his face, Frigga's words clattering around his brain.
He sighs.
He still has a mission to complete.
Steve sets the GPS again.
o-O-o
Steve lands at Camp Lehigh before he and Tony get there.
It takes less time to find a uniform and adjust his clothing to fit in. He had talked to Bruce about the security issues from before and Bruce had arranged a security pass to allow him to walk about the camp more freely.
Steve takes the elevator down to the storage floor. He hides at the back of the room and waits.
Tony arrives and the sight of him takes Steve's breath away. He watches as Tony scans the storage and finds the Tesseract.
He looks good.
He looks alive.
Steve is so thankful that he got the opportunity to mend his friendship with Tony before…he blinks back tears.
It's difficult to think that within hours of Tony taking the Tesseract that Tony will give his life to save everyone. The memory of Pepper's grief and of Tony's daughter's quiet confusion at the idea that her father is gone steals over him.
He almost misses the scene between Tony and his father.
For a second, Steve takes a moment to enjoy Tony's flustered response.
Howard Potts.
Steve rolls his eyes, glad of a moment's levity. He smiles as the two men walk out together. He and Tony hadn't spoken about it but he knows how much Tony had appreciated the opportunity to speak with his father.
Guilt rises up within Steve once more.
He should have told Tony the truth about his parents' deaths as soon as he found out; he should have…
He should have done a lot of things, but he hadn't. He has to live with the decisions he made.
It had cost him years of friendship with Tony. He hadn't been Uncle Steve to Tony's daughter; he hadn't really paid attention to the fact that Tony had a daughter.
More devastatingly, maybe Tony had been right that Steve's lack of trust in him had cost them everything and led to the first snap Thanos had made. Steve hates that idea but he can't discount the fact that Tony might be right about it.
He can remember the moment before Ultron when he had tried to move Mjolnir; it had warmed under his palm for a moment but then…it had gotten stubbornly heavy and he'd been unable to lift it.
Unworthy, because he'd been lying to Tony for months at that point.
Steve thinks back to the moment in the alley when Tony had asked Steve if Steve trusted him. Steve hadn't hesitated because there was no reason to hesitate any more. At that moment Steve hadn't needed to second guess Tony; he'd known Tony's motivations and his boundaries with the mission. The shadow of not trusting Tony because he'd feared how Tony would react about Bucky was gone.
Steve sighs.
He knows now with a certainty he hadn't had at the time that Tony could have come to terms with the knowledge that the Winter Soldier had assassinated his parents. Maybe he would have reacted badly in the first instance; maybe Tony and Buck would never have been friends. But Tony would have come around eventually, would have accepted it eventually.
He should have trusted Tony more.
He thinks that the moment he put his trust in Tony once more – that moment right there is when he became worthy to wield Mjolnir.
He shakes himself out of his thoughts and heads to return the stone. He grimaces as he looks at the stone sitting there in the storage unit. They had to break the crystalline structure to get to the stone so it's bare and not the actual Tesseract at all…
As though the stone has realised the issue, it glows brightly; a green light forming around it. A square structure snaps into place and Steve watches in amazement as the green slides away and the form it once had is resumed.
"OK," Steve murmurs. He resolves not to think about how it created its own cube too much.
He closes the unit and takes out a small laser welder from a side pocket. He welds the unit locks back together.
It's done.
The Space stone is back in its place in time.
He glances up to the ceiling.
Somewhere above him Peggy is working; she's here and alive. Steve could go and see her again. He could talk to her like Tony talked to his father…
But he can't.
Howard hadn't recognised his son because Tony was still to be born. Peggy would know him instantly on sight.
He can't have his moment with her.
He can't.
Steve sets his GPS. There is one final trip to the past to be made.
o-O-o
Steve lands in Stark tower just in time to see Hulk beat the crap out of Loki. He hides in a bedroom down the hall and waits.
Returning everything to its place in this time is going to be difficult.
He breathes in and remembers what Tony and Scott had told him about the difficulty with the Tesseract heist; they'd gotten downstairs, Scott had managed to zap Past Tony into letting go of the case, Tony had gotten the case and…and been hit in the face with a Hulk as he'd exited the stairwell. The case had gone flying, the Tesseract had ended up in Loki's hands and Loki had used it to disappear.
One timeline to snip right there; Thor had to take the Tesseract and Loki back to Asgard.
Then there was the sceptre.
Steve had thought he was being clever grabbing the sceptre from the STRIKE team by using the words Heil Hydra, but…how to return the sceptre and still maintain his lack of knowledge about Hydra…
They had come up with a plan. Bruce, Thor and he had brainstormed and Steve figures that their plan might just work.
When the Avengers arrive to take Loki into custody, Steve slips out and down the stairwell. He gets out at the next floor and takes the elevator to the ground floor.
He waits in an alcove, hidden from view.
When Tony appears again, it's less of a shock than the last time. Steve is able to simply enjoy seeing Tony alive and well…
And God what did Scott do?!
As Past Tony writhes on the floor, Steve watches as the case goes spinning away where older Tony picks it up and…
The Hulk emerges from the stairwell on cue.
Steve immediately emerges and runs out. He gets to the Tesseract just before Loki can reach for it.
"Ah, ah!" Steve says and carefully swipes the Tesseract from beneath Loki's fingers.
He heads over to replace it in the case and closes the case definitively. He can see the confusion on Tony's face; he's staring at him in disbelief.
Steve ignores him and hands the case to Past Thor as Past Tony struggles to his feet patting his arc reactor. "I believe this is yours."
Pierce glares at Steve. "Captain, that is the property of…"
"Odin," Steve asserts, "Red Skull told me himself that he stole it from a hiding place Odin created thousands of years ago."
Pierce looks furious.
"Thank you, Captain," Past Thor says dryly. "You are correct."
Past Tony motions towards a room. "Look, let's step in there and discuss this for a second."
Steve waves them off. "I'm going to continue search and rescue."
He waits until they disappear before he taps the radio he has in his ear.
"All teams be advised that there are reports that Loki has created a duplicate in my image to distract us," Steve reports briskly. "We think he has acquired the sceptre."
He's not surprised when Past Tony responds almost instantly.
"Cap, are you sure?" Past Tony asks. "We have Loki and…"
Steve heads to the elevators.
"My brother has been known to create duplicates," Past Thor interrupts, "it is within his skill set."
"I have eyes on Loki fourteenth floor," comes the report from himself.
Steve ignores the radio as he takes the elevator to the floor where he had ended up. He takes a moment to resize the sceptre. The Mind stone zips into its place and once again a green glow emerges to form a hard shell around the stone, returning it to its former position fully.
When he gets to the glass bridge, his past self is still out cold. He puts the sceptre beside him, takes a moment to admire his own ass again, and jogs away.
Once he's on the street, he checks the alley just in time to see a disgruntled Scott zipping away with the sceptre.
Steve takes a moment just to breathe and rest.
There is one stone left to deal with.
o-O-o
The streets of New York are a mess.
Steve navigates his way around rubble, burned out cars and buses, and the dead bodies of the Chitauri.
Bleeker Street is mostly undamaged and Steve wonders at that. He thinks about how Bruce told him that the Ancient One was on the roof helping to defeat the aliens. They'd had no idea of that back in 2012, but Steve figures that was the way the sorcerers had wanted it.
The door to the Sanctum opens as he approaches and Steve steps inside with some trepidation. He takes a cautious step into the hall and isn't truly shocked when the door closes behind him.
"We've been expecting you."
Steve turns back and finds an androgynous figure on the stairs. Strange had called her the Ancient One and had simply smiled when Steve had asked if he had any words of advice in dealing with her.
"Hello," Steve says, "I've come to return the Time stone."
The Ancient One nods. "Come this way."
Steve follows her through the Sanctum to a small sitting room. She motions for him to take a seat.
"You must be tired," the Ancient One says.
"It's been a long day," Steve admits.
The Ancient One hands him a cup of tea and Steve takes it. He sips it before setting it aside and resizing the case. He takes out the Time stone and offers it to her.
"Thank you," the Ancient One waves her hand and the stone drifts across the air. She takes it and places it within the pendant she wears.
Steve nods and picks up his tea. He settles into the chair, weary and heartsore, but satisfied that his mission is over. He can take a moment before he returns to the future.
"You have questions," the Ancient One notes.
Steve sighs and looks over at her. She seems so calm and collected. He wishes he could be like that. "Did we manage to snip all the time branches?"
The Ancient One hums. "In truth there is less we know about how the dimensions of our reality truly work than what we do know."
"I was kind of hoping for a yes or no answer," Steve admits.
The Ancient One smiles somewhat kindly. She gestures and a bright orange line appears in the centre of the room with six stones circling it. "You each took a stone from your timeline," she wiggles her fingers and the stones disappear, "and at each point there was a new branch created."
The orange line has six coloured branches sprouting from it at different points.
Steve acknowledges that truth; that they'd originally created six different branches.
"But it was not just the removal of the stones which created a branch," the Ancient One cautions, "there are interactions which occurred in this version of your timeline which remain, which also result in a branching."
Another few branches appear.
"Tony talking to his Dad," Steve said out loud one example, but his mind was filling with others; his interaction with Thor's Mom, Thor's interaction with her, the fight he had with himself over at the tower…
"In your timeline, the conversation never took place and Howard Stark doesn't talk about his fears of fatherhood," the Ancient One murmurs and reaches out to touch the branch that was created, "but in this branch, he remembers this conversation when his son is born and throughout his son's life; he takes care to be a better father."
Steve stares at the branch.
"But events still unfold here very much as they do in your own timeline; Tony Stark still loses his father and mother to the Winter Soldier, he is still betrayed by those he loves," the Ancient One's gaze flickers to Steve, "and he will still give his life to save the world against Thanos."
Steve sighs. "Is there any way to snip all the branches?"
"No," the Ancient One says, "that choice was gone the first moment you chose to return and interact with the events of your own timeline."
"So, this mission was for nothing?" questions Steve out loud.
"No," the Ancient One corrects him, "you have performed a valuable service in returning the stones to their origin points," she points at the glowing orange line and six of its branches disappear, "and so they are where they are meant to be; they continue to shape your timeline and this one."
"This one where Bruce and I both interacted with you," Steve notes. The only way they could have prevented branches completely was to have never interacted with anyone; to have simply removed the stones and immediately replaced them.
"A reality once experienced remains a reality to those who experience it," the Ancient One says.
Steve feels his breath catch.
"You should consider that before you make your choice," the Ancient One says.
Steve's eyes snap to her. "I don't understand."
"You dream of returning to your past," the Ancient One states simply, "you are a man out of time, Captain Rogers, it is not difficult to understand your greatest desire."
Steve feels emotion rise up within him and almost catch him off guard; the unfairness of his life; his inability to move on. "I had a date," he whispers.
The Ancient One nods. "Think carefully before keeping it, Captain Rogers." Her eyes are solemn. "Disturbing the natural flow of time has consequences."
Steve is unable to speak.
"Good luck," the Ancient One says. She makes some kind of sweeping gesture and Steve finds himself outside of the Sanctum.
He heads into another alley and sets the GPS for the future. He gets to the year before he stops and just…stops.
Would it be so bad? Would it be so bad just to take one moment for himself? If Thor can speak to his mother, and Tony to Howard, why can't he just take a moment to be with Peggy? One moment to be Steve Rogers and not Captain America; to be who he is and not who he is supposed to be.
One dance.
Just one dance.
How much of a difference would that make to a timeline?
His fingers are shaking as he inputs his destination.
o-O-o
Strange drops Steve off on a bench just a little way from where Bruce, Bucky and Sam wait for his arrival.
He blinks back his disorientation. One minute he's standing next to his desk, looking down at the letters he's leaving and the next…sitting on the bench with a single bag containing a precious gift. He pats his pocket where the disc of photos and videos is secure; reminders of the life that he has lived.
Behind him Steve hears Sam's concern as he doesn't appear and Bucky spotting him. It doesn't take long for Sam to approach after Bucky gives him the go ahead.
Steve feels a ripple of guilt as Sam takes in his age and realises what has happened. But Sam is a good man and while Steve can see he's upset at Steve's aged appearance and his decision, Sam is genuinely happy for Steve. He's a bit shocked when Steve gives him the shield, but the world does need a Captain America and Steve is too old to step up any more.
Sam slips away and Bucky sits down beside Steve.
"You really did take the stupid with you," Bucky sighs.
"It wasn't planned, Bucky, I swear," Steve says. "I just…I just wanted to make my date."
But then there had been an attack and Steve's quantum suit had been damaged along with the Pym particles. He had already told Peggy everything and with his means to get back to his own timeline gone, Steve had agreed to stay.
He'd gone onto live a full life.
He'd been able to do so much in the timeline his dance with Peggy had created: he'd prevented Hydra from using SHIELD as a Trojan Horse, rescued Bucky, been there for Natasha Stark, Howard's daughter (and hadn't that been a kick in the gut at the time). He and Peggy had loved and lived; they'd had children and had a grandchild on the way. But he had been unable to stop Peggy developing dementia or her inevitable death just a few days before. It hurts as much the second time as it did the first, but this time he has memory upon memory of her to soothe his grief. When Strange had turned up to collect him, Steve had figured it was the right time to leave and face the consequences the Ancient One had warned him about.
He's certain though that the timeline branch he'd lived within is safe. His own children lead SHIELD and the Avengers. His son carries Captain America's shield and he's married to Natasha, the Iron Lady. They're ready for Thanos thanks to Steve's warnings and they've already dealt with two potential invasions successfully.
Bucky looks at him; eyes serious and knowing. "You staying?"
Steve glances around, remembering the makeshift arrangements they've had to make because the Compound is gone. He remembers the battle with Thanos. He remembers Tony's sacrifice; Natasha's. He remembers how he couldn't move on; how he had lived his life in the past. He remembers just how much they have to rebuild here in his present once again.
He's left his children letters to explain his own disappearance. His letter to his son contains an apology and the coordinates of a man still trapped under the ice. He hopes the family he has built will help the Steve Rogers of that timeline move on in a way that Steve never could himself until his trip back in time.
He already misses the life he has lived with Peggy, but Steve feels the rightness of his own timeline settling back into his skin. He is back and he has friends who need him.
Steve places his hand on Bucky's shoulder. "Till the end of the line," he swears anew, "I'm with you till the end of the line."
The End.