Warnings: Spoilers for Infinity War, Major Character Death, Angst
Backstory: A What-If story based on if Peter and Groot had survived the Snap instead of Tony and Rocket.
Peter felt his Spidey sense blaring in his head, and he turned towards Tony.
They watched as Quill, Draax, and Mantis dissolved into dust. Nebula fell to her knees, a hand flying to her mouth, the only emotion she'd displayed besides anger and rage.
All at once, Tony staggered.
"Tony!" Peter gasped, darting to catch the man as he collapsed. "T-Tony, no no no, please, no-"
The man's chest heaved as his feet turned to dust. "Oh, god," he said numbly. "Peter, I-"
Neither hesitated from hugging each other, Peter clinging to Tony desperately as tears flooded his eyes. "Dad, please, I don't want you to go, I d-don't want you to go!"
All too quickly, Tony's grip was fading. "I love you, Peter," the man sobbed, and then dust was covering Peter's lap and hands.
And he screamed.
Nebula had luckily known how to fly the Guardians' ship, and she'd gotten Peter onto it. He was barely responsive, crying and shaking, refusing to wipe off the dust from his suit.
It took a week to reach Earth. Nebula had managed to stop at a trading post and bought enough food edible for a human with the money on board the ship. It had taken some convincing to get Peter to eat, but she'd done it, three times an Earth day, for seven days.
On the fourth day, Peter'd broken down again, and she'd lost her resolve. Nebula listened to the human child's story of how he met Tony Stark, how he'd become a hero, how he'd tried to protect his father.
When they reached Earth, Nebula landed in what Peter called 'New York City', on top of 'Avengers Tower'. He'd invited her in, and she'd accepted, having nowhere else to go.
Peter stared at the mirror in his bathroom. He looked exhausted, battle-weary, numb, and he splashed water on his face. Even though Tony had attempted to sell the Tower back when Peter was starting out for real as Spiderman, he'd bought it back to have a base in the city. Luckily, Peter had full access to the tower, and put it on lockdown before giving Nebula a pass that allowed her to access everything but the most important labs and the armory.
He called May, but she never picked up. Ned was gone too, and so was MJ. Peter had no idea who else to call, so he put out a signal that was specific to the Avengers only.
At the moment, Peter was sitting in the kitchen with Nebula, eating pancakes, discussing how he could potentially replace her robotic parts with safer, more comfortable prosthetics that would allow her to get rid of Thanos' influence. Nebula was interested, asking how he would do it and how long it would take.
"Steve Rogers, Natasha Romanov, Clint Barton, Bruce Banner, Thor, and two unidentified life forms are requesting access to the tower," Karen said from the ceiling. Friday had been gone, having disappeared with Tony, so Peter put his own AI into the whole tower.
Nebula stiffened, reaching for her sword. "Enemies?"
"Maybe. Don't hurt them yet, okay?" He replied, readying his webshooters. "Let them, Karen."
It was a stressful five minutes before the elevator dinged and the group inside was greeted by Spiderman and a blue alien-lady ready to fight.
Steve Rogers held up his hands. "We don't mean any harm," he said as calmly as he could. "Who are you?"
Peter's mask folded back and he bared his teeth. "Explain yourselves first. We can take you down faster than you can hurt us."
Natasha was the first to move, dropping weapons on the counter and sitting in the nearest armchair. "Deal."
Slowly, the other Avengers, a small tree-thing, and a blond woman wearing very cool armor followed her example. "I am Natasha Romanov, Black Widow," Nat said. "This is Steve, Clint, Thor, Bruce, Carol, and Groot."
A/N: ANGST. Carol is a strong, beautiful, powerful, funny, independent woman and that's the tea. Honestly, I'll probably continue this at some point. I want a revenge-seeking Peter. Also IRON!DAD FOR THE WIN