Hello, everybody; ModernDayBard here!
Of all the chapters, this was the hardest to write, and the hardest to determine the breaking points (I wrote the whole story as a single document, then decided where the chapter breaks should go). The first few scenes felt like pulling teeth, and didn't quite turn into what I'd envisioned when I thought of including them, but things picked up when I got to the last few scenes, and they turned into more than I'd been expecting, so I guess (or hope) it all balances out.
Disclaimer: I don't own Marvel, their characters, settings, McGuffins, etc. I own the ideas I suppose, as much as anyone can (though they've been heavily influenced by listening to discussions and reading other fics) and the words that I have chosen to narrate with.

Natasha was…less than pleased when they returned.

On the previous few occasions he'd had facing the wrath of the Black Widow, Clint had furiously apologized, usually while fleeing the area, at least until she calmed down. But now, he stood there, and let her glare and mutter darkly about what she'd do to him if he ever worried her like that again. It wasn't like anything she could—and especially would—do to him could compare with what he'd already been through, and soon enough his best friend could tell that his thoughts were flowing down those lines and stopped, letting her true worry—not just for the past day, but for him in this new, horrible half-universe—show clearly, if only for a moment.

"Just tell us next time, Clint. Let us know you're coming back."

He shrugged. "Don't have much anywhere else to be, do I? The kid just needed to go home, everyone else was busy."

At that, the two glanced over to the other huddle, where Peter was on the receiving end of worried lectures from both Steve and Rhodey, while Nebula stood some yards away, arms folded as she tried to project a deliberate air of nonchalance—not very successfully.

For his part, Peter was trying to keep up with both lectures while not falling apart—he may have needed to go, but that didn't mean that all those farewells left him in a particularly good mindset—and all he really wanted right then was some time alone to process, though whether that would be by yelling, hitting something, or pouring himself into the mission now, he couldn't honestly say.

He was surprised that Captain America even noticed him, much less cared that he'd vanished for most of a day, and by the concern in both his and Col. Rhodes' voice. He'd only met the two less than a handful of times each, and he hadn't thought anyone really took note of him, besides Mr. Stark. In a happier circumstance and better frame of mind, he'd have been ecstatic at this sign of inclusion. As it was, it was all he could do not to physically run away.

"We saw Miss Potts," he said quietly when both men paused for breath at the same time, allowing space for something to be said. "She's—" he stopped, about to say, 'holding it together, kinda' (because weren't they all?), but what actually came out was, "alone." He almost felt the stares and added, "Happy's gone, too."

The captain frowned, the colonel just closed his eyes, able to put a face to this new loss. Surprisingly, it was Nebula who spoke up. "If you're in, you better get moving. Lots to do before we're ready, and you're behind now."

Peter nodded, not so much feeling better as much as clinging to having something to do. It was time to test theories, to keep promises, to save the universe, or at least avenge it, time to charge to the last taunting hope they had, knowing it would likely vanish before they could grasp it:

It was time to go fight Thanos.

Under any other circumstance, at any other time, the fact that he was sitting in the lab of the Princess of Wakanda herself, surrounded by technology he could only dream of (including several pieces that looked like some daydreams he had actually doodled in a notebook, once), with the person who built them right there for him to ask about any of them would've had Peter talking a mile a minute and bouncing like he'd had way too much sugar.

Under any other circumstance, at any other time, the fact that someone her age who could understand what she was doing and follow all of her technical explanations and tangents, would have had Shuri peppering this newcomer with explanations and questions both.

As it was, they were both quiet as Shuri looked over the suit Mr. Stark had given him just as this all started and Peter watched her work. There were workstations for a few other people, but the two teens were the only ones in the lab deep in the mines, and Peter supposed that the girl before him had lost a lot more people than just her older brother, but like him, she was trying to focus on what could be done, rather than what had been done.

"Other than the structural damage, there aren't too many improvements to make—at this time," she added, with a half-hearted smirk that indicated an inside joke with…someone. "You built this?"

Peter shook his head. "Mr. Stark. I built my first one, but he made the others…"

His voice trailed off as his thoughts threatened to spiral back to New York and his encounter with Pepper, the loss of Happy—

"Tell me about it."

He looked up, surprised, to find Shuri staring right at him, an odd look—a knowing look—in her eyes. When he did not speak at first, she repeated herself. "Tell me about your first suit. What you tried, what you built—why you did it the way you did. It's too quiet in here. I'm used to chatter while I work, and all you hero types are the stoic, silent ones right now. I need some noise."

For a moment, he saw beneath the strong mask the young scientist in front of him projected, and realized his assessment was right: there normally were far more people working with her, here. Slowly, hesitantly, he began his account of his early days as Spiderman, feeling ashamed of what now felt like meager steps, surrounded as he was by the results of her genius, even as she worked on a suit that far outstripped his own. But then she started interjecting, asking questions about why he did thing the way he had, and as the two got into a technical discussion, he was surprised to find her actually impressed by some of his more…unorthodox…solutions, and by his chemical dabbling to get the web fluid just right.

"You certainly made the most of what you had. You know, when you all get back, I may need to have you out here again. Or at least, help me get the outreach center in Oakland running. I've got some ideas I want to run by you—ideas that some people here are too cowardly to try," she added with a teasing glare at one of the other workstations, though its emptiness sobered her a half-second later.

She thrust the suit into his hands. "I've repaired all the structural and system damages and made sure you're linked into the COM network I'm setting up for everyone. Anything else will have to wait until next time."

With that, she firmly ushered him out of the lab, but it was not lost on him that twice now she had spoken of their return in terms of 'when' not 'if'.

He could only hope.

Is anything lonelier than the night before a hopeless battle?

The preparations that needed to be done—at least, that could be done—had been seen to, tomorrow morning the final assembly would gather, and Thor would use his magic weapon to open a pathway to Thanos. And then?

Who knew.

After Shuri's lab, Peter had broken away for a little solitude and still sat perched on the rooftop he'd climbed to, staring out over an incredible vista, but seeing none of it. The sun was slowly sinking, painting Wakanda a million impossible colors, but all Peter saw was a tiny New York apartment with three people inside, trying their best to keep each other safe, all three alone in this horrible new reality. Or else, he saw an empty and dead planet, felt his throat burn with ash and tears—

"Trying to give us all another heart attack?"

Peter whirled, surprised that the voice had been his first clue someone was approaching (normally, his heightened senses picked up footfalls, etc., but he had been distracted), and that the voice belonged to Captain America—who then sat down beside him, feet dangling over the edge, staring out over the field that Peter only just now realized had been the sight of earth's battle against Thanos.

After a moment, the older hero, also dressed in civilian clothes, kept talking. "If one of the Dora Milaje hadn't seen you come up here, Rhodey would probably be freaking out about your second disappearing act in a single day."

Peter glanced away, ashamed he'd caused people to worry—let alone twice—but also surprised that there was anyone here who'd miss him in the chaotic bustle of war preparations. "I—needed some air," he managed at last.

The captain nodded. "Figured as much. I told him I'd check on you in a few hours if you hadn't come down."

"Why?"

He hadn't meant to ask, but it had slipped out while he stared at the legend beside him. For a long while, Cap just looked at him with an inscrutable expression. "It's what a team does."

"But I'm not—" Peter began, then stopped, afraid of how finishing that statement would come across. He rephrased. "I'd told him I wasn't ready. I was staying small-time. I'm not import—"

This time, it was Captain America who cut him off. "Yes, you are. And you're here, so you're an Avenger now."

The words triggered a memory, and he had to look down, out—anywhere other than the man beside him. "Captain—"

"Steve," came the correction. When he looked up, surprised, Cap gave a lopsided grin. "I'm not actually all that big on rank. And now that you are one of us, you can call me—"

"Friend Rogers!"

The two turned to see Thor had joined them on the roof. Cap started to stand. "Thor, did you need—"

The god of thunder sat on Captain America's other side. "Just needed to get away from…" a handwave indicated everything of the chaos below, and the two already on the roof nodded their understanding, even as Peter mused it might get crowded up here soon, unless people started seeking out their own rooftops.

Thor seemed to notice the boy for the first time, leaning around Steve to acknowledge the team. "Hello. Sorry, I never caught your name—there are a lot more of us than when I left."

"I'm Peter," he answered. Then, almost as an afterthought: "Spiderman."

The Asgardian nodded, filing the information away, trying to place all the newcomers. "Ah. Then you work with Scott—Ant-Man?"

Peter shrugged. "This would be the first time—I'm kinda new here. Newer than anyone else, I think. The names are just a coincidence."

"Ant-man, Spiderman, Black Widow," the captain ticked each name off his fingers. "Scott also mentioned a Wasp."

"And there was Mantis, so the phenomenon is not limited to earth," Thor put in, leaning back a little and staring up at the stars as they emerged into the sky.

Peter felt a jolt, a face springing to mind. "She was the one with antennae? With the—the—" Why were the names evading him?

"The ones who called themselves Guardians, yes. Rocket's friends."

Peter pulled his feet up, wrapped his arms around his legs and rested his chin on his knees, unable to tear his mind away from the dead planet. "She seemed…sweet. Like a kid, almost."

"She was an idiot. They all were."

Three heads turned to peer past Thor to take in the furry form of Rocket coming to join the party. "And naïve? The girl would believe anything anyone told her. We took her in because there's no way she'd survive on her own in an uncaring universe. She has literally zero survival skills." For all he was bad-mouthing one of his teammates, there was no vitriol in his expression, though he feigned it in his tone. "She and Drax got along great—what with him being so literal and never doing anything but charging head-on. Guy was all muscle, no brain. He actually thought Quill was the smartest guy on the team. That knucklehead! All music and references that nobody gets, joking about everything instead of taking it seriously. And Gamora—always poking her nose into everybody's business, like it was her job to mother us or somethin'…"

His rant had been gradually losing its energy, and he appeared unable to even mention the final member of his team. "They were all idiots," he concluded in a tiny, choked voice. "But they were my idiots."

The four sat in silence. No one offered any 'we might get them back'. That was a small hope hinging on the small chance they could actually beat Thanos, a possibility that seemed remote, even unreachable in that dark night above the too-empty battlefield.

Is there anything lonelier than the night before a hopeless battle?

Ned, if you're getting this message… I'm sorry.

…I really don't know what else to say.

We tried, I swear. I tried to bring them back. But this Thanos guy is strong. Hopefully, we at least set him back enough that he won't do anything like this again. Even if he does stay away, I know things are, well, shit right now. And I don't think the world we knew will come back. But you're smart, man. You'll make it. Just, please—

I know I don't have grounds to ask this after I didn't save—but please, please, look after May. I know she'll take you in, but she needs someone to take care of her, too. If you're getting this, I can't. So, please…

And thank you. Thank you for being my Man in the Chair. And my friend—my best friend. I'm sorry for all the crap I've dragged you into over the years, but I'm glad I had you by my side. There just aren't—I don't know what to—

Just keep living, okay?

…..

MJ…

I'm sorry about prom? I'm sorry about a lot of things, honestly.

I don't honestly know how I ended up with you as a friend, but I'm glad I did and sorry it took so long. I wasted a lot of time.

If you're getting this, we failed. We failed, and we can't fix the world, so things are going to be so wrong for a long time. But you're strong—please, help Ned and May to stay strong, too. And you can ask them for help, when you need it. You don't have to stand alone all the time.

(Oh, and if Flash ever gets up to his old shit, give him hell for me, okay? You know, with your patented MJ flair.)

…..

Aunt May…

(Oh, God, I can't do this…)

I'm sorry—for everything, I am so, so sorry! All the trouble I've been, all the worry I caused, all the times I disobeyed or lied to you. I should have been there for you more, should have helped you more.

Everything good about who I am today is because of what you taught me and how you raised me—and I'm so sorry about the rest. There is so much I owe to you, so much I should've done for you instead of going gallivanting across the galaxy.

But I have to believe there was a chance to fix this. We had to try. I didn't mean to leave you alone. I love you so much.

Please stay alive.

I love you.

…..

Peter turned off the recording, then jumped as the door opened behind him.

It was Col. Rhodes entering, and the older man took in the tear-streaked face before him with no trace of judgement. "Kid, you don't have to come. You've got people waiting for you," he said, with a gesture at the computer on which he'd been allowed to record his 'just in case' messages, along with any of the other heroes who still had people to leave them for. "You've got years ahead of you—"

"In what kind of a world?" Peter shot back, surprised at the vehemence in his tone. "My two best friends are orphans, now, and I know what that's like. If there's even a chance I can bring their families back—Mr. Stark—Happy—anyone—then I have to try!"

Spare the boy, and I will give you what you want…

With great power…

It had to be this way…

…comes great responsibility.

…We're in the endgame now.

He gave up the Time Stone for me. There has to be a reason, or at least something I can do to make it right.

Col. Rhodes didn't say anything more, but gestured for Peter to follow him to where the remaining heroes were assembling, clearly unhappy, but at least understanding now, if only a little.

So, yeah.
I wasn't expecting much from those last two scenes, and they've got to be some of my favorite in the story so far. And especially in the last scene, the moment with Rhodey—if I was being honest, until that point I couldn't tell you why Peter was going to fight Thanos instead of protecting the people still alive. I mean, yes, I had him saying they had to try to bring people back, and I knew that really was his reason, but I couldn't verbalize why that was so strong a reason for him, given how much he didn't want to leave May and the others behind. But then…then I realized why finding out that Ned and MJ had lost their parents was the tipping point that set him on this path. Then, of course, with Uncle Ben's motto and Dr. Strange's vague hints running through his mind—yeah, Spiderman's going to fight Thanos.
I guess I found it kind of funny that I knew and didn't know at the same time—I knew what was true, but I had to find out why. My only regret with this chapter, in the end, is not feeling like I did the potential dynamic between Shuri and Peter justice. Maybe it was the circumstance, maybe I'm not the person who can write that exchange, but I had higher hopes for that scene. Oh, well.
As always, if you saw something you liked, or something you think I can fix/improve on for next time, don't hesitate to leave a review and let me know!