Hello, everybody; ModernDayBard here! As soon as I came up with the concept for this series, I this was the second scene I came up with—I knew I had to do it. But now that the time has come to actually write it, I'm nervous. I'm hoping it comes as easily as the others did because, like the last chapter, I don't really have much of this story worked out in my head pre-writing.
Disclaimer: I don't own Marvel, or anything they own that appears below. I don't even work for them. The only thing I do own are the words I used—I'd say the ideas, but these are probably what-if's that many other fans likewise imagined their own versions of.

Chapter 4: Father

Gone. Slipped through his fingers.

There'd been a moment—a single, beautiful moment—when it seemed like they had won. When he felt the gauntlet budge, then slide towards him, coming off the purple giant's hand. Then this Thanos guy had roared, shaken the others off, pulled the golden gauntlet out of Peter's grip, and slammed him with a powerful back-handed blow, knocking him away like he really was some kind of bug.

After Peter shook off the blow, got his breath back, and jumped back in, the rest of the battle became something of a blur. At one point, he knew he was swinging about, catching their odd new allies as they tumbled through the odd gravity of the dead planet (which had taken him a moment to adjust his swings to for the different momentum and resistance), and it struck him that he didn't know their names—or couldn't remember them in the moment.

Sure, maybe it was a small thing, but May had raised him to be polite and friendly to everyone (besides, he was the 'friendly neighborhood Spiderman'—it went with the job description!) but practicality (a voice that sounded like a slightly less-snarky Mr. Stark) told him he could save the manners for after the fight was over.

While he did that, Iron Man had kept fighting the Big Bad with the help of that wizard guy and the blue girl—wait, when had she show up? Sometime during their attempt to get the gauntlet, or was it just before?

Peter wondered if his memory issues, and the fact the fight seemed to be little more than a few scattered crystalline moments in an otherwise murky blur were side-effects of a concussion, or if it was just the normal effect of battlefield adrenaline. He should probably ask Mr. Stark about that once this was all over, except, if he did that, the older hero would actually test him for a concussion, probably freak out, and might even take the suit away…again. Or at least, ground him for a bit from patrolling.

"I mean, it probably is adrenaline—'cause I know I'm saying all of this out loud even though nobody's listening to me because this really is how I keep sane in high-stress situations, and I definitely say this qualifies."

None of the three he was grabbing made any sort of reply to this rambling monologue (after all, they looked to be dazed or unconscious), but as he grabbed the girl with the antennae (those were really cool!) she actually opened her eyes and looked right at him. "Uh, hi." He managed. "You alright?"

She glanced at the fight still going on behind them, then back at him and gave him a small smile. "Brave."

"I'm sure you are—" Peter started, before she reached out and placed her hand on the side of his mask.

"No," she said, still smiling. "We are."

A little of the fluttering in his stomach subsided, and that urge to help that drove him every day to don the suit and swing through his city flared up stronger than it had in a while (several minutes, at least) and he turned back to the main fight just as the purple guy blasted the wizard away in the middle of a really cool, really trippy-looking spell.

He saw an opening—an easy swing, actually—and without hesitation, he took it, slamming into the Big Bad feet-first with all of his bodyweight and momentum behind the impact (not that his bodyweight was all that impressive, especially with the wonky gravity on this planet, but the sheer surprise of a metal-clad teenager propelling himself into your face is enough to at least surprise most people, and that surprise should've been enough time for the wizard and the others to recover—right?).

But the giant grabbed him in some kind of blue aura and flung him away. Peter tumbled, then was back on his feet ready to run in behind Mr. Stark and Blue Girl as they launched a tandem attack.

The girl was knocked away, and Peter saw his mentor slammed into the ground with a crunch and several smaller but no less painful cracks, and he sort of lost his train of rational thought as he charged in, trying to buy Mr. Stark time to get up (oh please, please get up and be okay!).

It seemed he actually caught Big Bad off-guard, and for the first fight since receiving his powers, Peter Parker did not pull his punches. This guy wasn't human, and nothing else they were throwing at him was making much of an impact. He had time to land five blows, any one of which could've killed a human, then his right arm was seized, twisted, and broken.

Peter screamed—he couldn't help it when he felt the bones crack and shift against each other—and he felt more than saw or heard Mr. Stark behind him, but before Iron Man could say or do anything, a blast of purple energy knocked him backwards again, then all of the giant's attention was on him again.

"All that for a single drop of blood?"

Peter glanced at the strange face above him and saw that, for all he'd thrown at the threat, only a single wound—barely more than a scratch—existed to show for his effort. His stomach roiling from the pain in his arm, which was still being held so tightly, and it was all he could do to stop a whimper from escaping. They'd been so close.

The purple face loomed large, frowning. "A child? I'm impressed…and disappointed."

He flung Peter to the ground and, before the boy could think, he'd caught himself at least partially on his broken arm, tearing another cry of pain from him involuntarily. He saw Mr. Stark struggle upright, trying to jump back into the fight, but hampered by his own injuries.

It seemed to Peter afterward that he noticed three things simultaneously, even though some of them must have happened before others. He felt his Spidey-Sense send a jolt up his arms (for the second time that day), he saw Mr. Stark's eyes go wide (wait—when did he lose his mask? Was that safe?), and he felt the dagger-sized piece of scrap metal (was that a piece of Mr. Stark's Suit? His? Their space ship? Something else? Did it matter?) that Thanos stabbed him with from behind, piercing through his suit twice (back and front), which didn't seem like it should be possible, but they were fighting a giant purple alien for a bunch of magic rocks, he supposed he could let it slide.

Next thing Peter knew, he was sitting on the ground, facing the purple guy again, broken arm wrapped around his bleeding abdomen, staring at Mr. Stark's back as his mentor stood between him and the threat, both repulsors blasting.

The purple aura blocked the charges, then a blue one flung Iron Man away like he was little more than a rag doll, and then suddenly there was no one between Peter and the looming giant.

"When I am done, half of humanity will still live. I hope they remember you all."

The gauntlet was raised then, and Peter squeezed his eyes shut, praying that he could hold in any noise of pain or fear—that'd not be a great way to go out, even if that was how he felt.

"Stop."

The wizard didn't shout, but his voice held such authority and certainty that everyone turned to him, even the bad guy. They all saw the green stone he was holding out, and stillness fell for the first time since Thanos' arrival.

"Spare the boy, and I will give you what you want."

Peter stared, wondering if he was already delirious from blood loss or something—this was the same guy who'd said on the ship that he wouldn't choose him or Mr. Stark over the Stone (yes, he did hear that—Mr. Stark seemed to forget what Peter'd once told him about his senses being dialed up to 11 after he got his powers). The Big Bad seemed surprised as well, but shook his shock off first, and seized the stone.

A blue portal opened behind him, and he was gone, leaving his defeated opponents on the dead planet.

Peter was still staring in shock at Dr. Strange, who now sat still, eyes closed, as if he was… waiting. He'd seen so many versions of events, only one where they won. Whichever track they were on now, or on still, he'd seen what was coming next. He was waiting for it. Had they lost, and he was waiting for the end? Or did they always lose here and win down the line? Why did he give up the stone, if it was the key to winning?

Why did he give it up for me?

All those thoughts crossed the boy's mind in the time it took for Mr. Stark to scramble to his side, gently try to shift the injured arm to look at the more life-threatening wound. "—id, help me out here. Let me see what we can do."

Peter re-focused on his mentor in time to hear the whispered, "Shit."

"'S not as bad as it looks," Peter tried, but his protest wasn't convincing, what with the fact that all he could manage was a strained mumble, and that, immediately after he forced the words out, he coughed, and a little blood trickled from the corner of his mouth. (That was never a good sign, he knew enough to know that.)

"Peter, stay with me, stay focused," his mentor urged, his own voice taut with barely-suppressed panic. "Can you seal up the entry wounds with your webbing? Buy us some time, at least?"

Peter blinked, glancing down at the bloody gash. "But that'll only stop the exterior bleeding. I'll still be bleeding inside, and whatever organs that blade hit—" One look at Mr. Stark's expression told him that the older man knew, (of course he did), and that he'd been doing everything he could not to think about how close Peter still was to dying. "Sealing the wounds. Might be able to make-shift a cast for the arm, too, if you help me set it."

In the scope of things, a broken arm wasn't life-threatening, wasn't serious, might not even be important, from certain perspectives, but it was something fixable, and Peter needed something that could be fixed right there and now, and it seemed that Mr. Stark understood that feeling.

God, it hurt to set the arm—almost as much as breaking it or landing on it had—but the web-based cast actually seemed to be holding it steady, and Peter trusted that Mr. Stark and FRIDAY together had set it correctly, so he might not have to go through the whole thing again when—if—they got back to earth.

Scrabbling and scrambling sounds caught his attention then, and he looked up to see the rest of their allies had picked themselves up and where converging on the three earthlings with dazed, confused expressions that echoed the question that was hammering around in Peter's skull, too: What now?

Suddenly, antennae-girl's black eyes widened in something like fear. "Something's happening."

Then she just crumbled, vanishing into dust, and Peter choked back a horrified cry, surging to his feet and swaying.

What's happening?

"Quill."

Peter's head snapped around and watched the bald, muscled guy also crumble. The teen could feel himself shaking now with horror, confusion, and fear in one stomach-turning sensation. The other Peter didn't even get to say anything as he followed his teammates, and it felt harder and harder to breathe.

Had Thanos gotten the other stones? Was it over? Peter turned to the one person who seemed to know what was going on with the weird rock thingies, only to see that the wizard was dissolving like the Guardians.

Dr. Strange must've seen the question he didn't have the air or will to voice, because he held his gaze and gave as much of an answer as he could: "It had to be this way. We're in the endgame now." Then, he couldn't talk anymore, but it seemed like Peter could hear two more, unspoken words in that final gaze: I'm sorry.

He wanted to be home—he wanted this to be some sort of vivid nightmare he was dreaming on the bus—he wanted someone to tell him that everything was going to be alright. But it wasn't—was it? The wrongness of it was washing over him, choking him. Worse, a sense of dread was twisting in his damaged gut—not his Spidey-Sense, something deeper, more frightening.

He turned, then, to the only person who was any sort of comforting presence on this alien place, only to see that his mentor was standing too still, too stiff.

"Mr. Stark?"

The adult turned slowly, carefully, and a few wisps of dust were already peeling away. "I don't feel so good," he muttered, half to himself as if he wasn't really aware that Peter was there.

No! Nononononononono!

There were only a few feet between the two, but with one injured and one dissolving, it took a monumental effort on both parts to close the gap. A heavy hand crashed onto Peter's uninjured arm, with more of Tony Stark's weight behind it than the older hero had probably intended, but at least his gaze was focused again, grounded in the present, and fixed on the horrified face in front of him.

"'S going to be alright," he lied, and the lie an adult was supposed to tell a kid when everything was going wrong fell on deaf ears, because the teen had seen too much to believe it any more, however much he wanted to.

Peter clung to the man in front of him desperately, holding on as tight as he could, as if that somehow would stop and reverse what was happening in sickening slow motion. "Don't go," he pleaded, voice thick with tears he'd begun to shed without realizing. "Please, don't go. I don't want you to go—I don't want you to go!" He was begging now, babbling, but he couldn't stop.

Suddenly, he'd fallen to his knees, unable to hold the both of them upright much longer, and the man in his arms was almost gone, seemingly unable to speak. Peter shook his head, still crying, when an even worse thought struck him: If Thanos had done this (and who else could?), then he'd only been able to because Dr. Strange had given up the Time Stone… to save his life.

This is all my fault.

"I'm sorry," he wailed, just as what was left of his mentor crumbled away, leaving him alone, devastated, curled up on himself as his whole frame shook with terrified and guilt-laden sobs.

This is all my fault.

If he'd stayed on the bus, he wouldn't have been there at all.

This is all my fault.

If he'd gone home when Mr. Stark told him to, the older hero would still be alive.

This is all my fault.

If he'd been just a little bit faster, gotten the gauntlet off of Thanos' hands, this never could have happened.

This is all my fault.

If he'd been a better fighter—If he'd done something different—If he'd been good enough—

If he hadn't let it all slip through his fingers…

So, yeah. I've said it before, I'll say it again: these aren't happy stories.
This one was an interesting thought exercise for me, because it wasn't as simple as having to reverse who faded and who remained, like the last two chapters. After all, in movie canon, we get some kind of hint that Tony is vital for the success of the team in the next movie, so he can't be allowed to die, from their perspective (especially Strange's). That meant, in this version, Peter has to be the key, and that changed things a little further back, hence the fight going a bit differently. So, as much as Peter's blaming himself, it had to happen this way...
Honestly, the hardest point was picking a stopping point: I've seen so many great fics with Nebula and Tony having to get themselves back on their feet/reuniting with the team on earth that I wanted to give Peter that sort of a moment, too, but then I wouldn't know where to stop. That was my problem with the first chapter, too. Both of them could be their own full-length AU's, and I am more tempted to write those than I have been for any full-length fics in the recent past but…we'll see.

For now, I am done with this story. I know I said at the beginning there was another I thought I should do (Steve/Bucky, in the interest of full disclosure) but honestly... I don't know if I have enough feel for the characters/that moment to add anything there, so I'll end the story here, with four chapters I am proud of, and hopefully that you all enjoyed!
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!