Disclaimer, I've just thrown this together as an idea and I'll have more added to this later on today so be patient if you will and hopefully it will e worth it for you
We open in avengers tower, Reed Richards, Tony Stark, and Hank Pym are gathered around a table on which lay Natasha Romanoff, unconscious.
"I still don't understand it, Tony" Reed began. "Why would she turn on Barton like that?"
"Believe me, I'm just as confused as you, have you run a brain scan maybe there's something we've missed."
"I've already ran three, Stark!" Hank added. "There's nothing out of the ordinary, her brain is just as it was five days ago. Maybe we need to accept that fact that one of our own as gone rogue!"
"Seeing that it's Natasha that wouldn't surprise me in most cases, but this is different she would just attack Barton they're too close."
"Tony's right Hank, This is out of the ordinary even for her."
"And how is Barton does anyone know?"
"Last I heard from Sam he wasn't doing too well" Tony clarified.
Suddenly the monitors all throughout the tower started blaring with alerts of riots all over New York. Hank had set down his tools and opened the alert reading it in more detail.
"This isn't good!" He exclaimed. "Half the cities fighting, there's already been three casualties and it's getting worse!"
"Jarvis! Tell Parker, Cap, and Vision to get down there and have backup as soon as possible see if you can reach Thor."
"Of course sir."
"Are you sure that'll be enough, Tony?" Reed asked.
"It's gonna have to be, with the way things have been lately we haven't gotten the time to waste resources."
"Alright, I just hope you're right. Let's see if we can't find out what happened to Natasha."
Times Square, New York City, New york: 11:37 p.m est.
"Everyone please calm down!" Captain america said sternly. "Once again please calm down!"
"It's not working Steve, what's gotten them so up in arms anyway?"
"I'm not entirely sure Spider-Man, But something doesn't seem normal."
"Perhaps, they've been infected with some kind of virus." Vision intrigued
"You're saying a cold did this?" Spider-man asked. "That's gonna be a lot of chicken noodle soup to cool them off."
"I'm not sure what exactly is going on but the sooner we find out the better" Cap said
"Cap! Watch out!" Spider-Man exclaimed.
Suddenly a car came barreling down the middle of time square just missing Captain America. The car slammed into a building taking four people with it. Cap, Peter Parker and Vision walked over to the accident and were shocked at what they saw. Millions of tiny green particles were floating around the scene. The particles were almost too small to see but with a careful eye you could easily tell there were there.
The three heroes backed away from the scene and watched as the particles came into contact with all the people around them, and as the particles did so anyone affected immediately became violent and reckless.
"Tony, I think we may have discovered what's causing this mess!" The Captain radioed in.
"Good, what is it?"
"It seems to be some sort of extremely tiny parasite."
"Huh, that's interesting, you're sure you didn't come into contact with it right, Cap?"
"Positive!"
"Alright, get back to the tower, let's see if we can figure something out, there's not enough of use to stop all the riots."
"On our way!"
Avengers Tower, Manhattan, New York City, New York 11:43 p.m
Sam Wilson walks in from another room with sadness written on his face. Tony Stark notices him coming and makes his way towards him.
"He's gone, Tony."
Tony stops dead in his tracks and falls to the floor "No!" He screams. "First it was Nova then Miss Marvel, Beast, Nightcrawler, Rhodes, Susan Storm, and now Barton. What is happening to us, how have we let our guard down so much to let all of our friends die, right before our eyes."
"Tony, please, I know it's hard but we have to figure this out everything will be okay soon enough" Cap said in an effort to calm him down.
"But what if it's not okay, Steve, what if they keep dying, what if we can't save them. You saw what happened to Natasha, Thor and Cyclops. And now people are dead Thor's and Cyclops are missing and Natasha is dying on that table over there!"
"I'm well aware of the circumstances, Tony but if we don't do something about it now, they will never rest peacefully knowing we didn't do our job!"
"Steve's right, we can't sit around while the threat is still out there." Reed agreed."
Tony exhaled slowly collecting his thoughts as the machine monitoring Natasha's heart rate fell to a long single beep. "Turn it off!" Tony demanded. "Turn it off, now!" he began to hyperventilate and sweat profusely. "Jesus, damn it someone turn that thing off!" Hank Pym reached down and unplugged the machine. Everyone's eyes were now fixed on where Tony lay sobbing on the cold floor of the tower.
"Mr. Stark, I highly advise you get some rest, You haven't slept in nearly fifty-six hours." Vision stated.
"I'll sleep when our friends stop dying! Don't you guys care at all?"
"We care Tony believe me, we're just trying to weigh all of our options right now." Sam added
"We'll it sure as hell doesn't seem like it!"
"Tony c'mon they were our friends too, we can't show weakness at a time like this is all." Peter Parker said frantically trying not to cry.
"Captain, what was it that you three saw in Times Square? Maybe it has something to do with this." Reed asked avoiding the current conversation.
"Oh, right! It seemed to be some sort of parasite or something, I couldn't really tell. Whatever they were, they were smaller than anything I've ever seen, and there were millions of them!''
"Hmm, I don't think I've ever heard of anything like that. Maybe if we get a sample of them, we can do more research."
"What are you suggesting, Reed?" Peter asked.
"I'm suggesting that someone goes back to Times Square and collect a vial of the stuff. That is of course, if it is still around.
"I'll go!' Steve and Peter said in unison.
"Alright, but be careful you two, we don't know what we are dealing with, I'll see if I can calm Tony down while you're gone."
Times Square, New York City, New York 12:17 a.m.