Author's Note:
The following events take place during the first Avengers movie.
Most of the movie's events remain the same unless otherwise stated, though I may reorder some of the chronology for the sake of pacing. I jump around through the story so this works better if you remember the movies well.
Of course, Marvel owns all the rights to these characters, and there will be spoilers for the films involved.
*********
For the first time in what felt like weeks, Natasha felt like she had a clear head. As she strolled across the Helicarrier's runway, the cool sea air made her feel fresh and ready for whatever trouble the day was likely to send her way.
It didn't hurt that last night's... activities... had released a tension in her body that was interfering with her work. If she hadn't sorted that out, she wouldn't be on her top form today. It might have been a slim justification, but it was enough to keep her feeling positive about the whole thing.
If it wasn't for the rest she finally achieved last night, she might be a little freaked out that she was about to meet one of the most important men in history.
She arrived just as Coulson was disembarking the quinjet, looking like he was trying his best to remain cool and casual, holding all his fanboy excitement inside. Next to him was none other than Steve Rogers, better known to the history books as Captain America.
"Agent Romanoff," Coulson stated, as the super soldier's eyes wandered around the impressive airship, "this is Captain Rogers."
"M'am," Rogers stated, addressing her as properly as she imagined someone from the 1940s would.
"Hi," she bluntly replied, before telling Coulson he was needed on the bridge. He left her to escort his passenger the rest of the way - but they had one more team member to pick up first.
"There was quite the buzz around here, finding you in the ice. I thought Coulson was gonna swoon. Did he ask you to sign his Captain America trading cards yet?"
"Trading cards?"
"They've vintage, he's very proud."
They came across Bruce Banner, who was nervously side-stepping the countless S.H.I.E.L.D. staff preparing the strip. Rogers immediately approached the doctor, asking him questions. Natasha let them have their moment, knowing from Banner's darting eyes that he wasn't entirely sure how to speak to her after their last confrontation.
"Gentlemen, you may want to step inside in a minute," she eventually interrupted. "It's gonna get a little hard to breath."
The Helicarrier started to shake, its innumerable moving parts creaking as it prepared for take-off. She couldn't help but smile as the two men, who had seen the most strange of scientific advancements, were stunned by the turbines rising from the water.
When they arrived on the bridge, they found hundreds of agents sweeping every wirelessly-accessible camera on the planet, with anything connected to a satellite at their disposal. But it was a slow method of finding Loki, and they needed Banner to speed up the process.
Luckily he had some ideas for tracking the tesseract, so Fury asked her to escort him to his lab so he could get down to work. She followed the orders promptly, though she was slightly put off by the glare Hill was giving her from across the room. 'I knew that latte comment was going to bite me in the ass,' she thought to herself.
"You're gonna love it doc, we have all the toys," she remarked, not making eye contact as he led him down the hallway. The short walk was silent and a little awkward, but Natasha didn't let it show. Eventually, Bruce spoke, though she didn't have time for the chit-chat.
"So... about Kolkata -"
"I'm going to stop you right there, doctor. We don't need to talk about it. It's in the past. We're all good."
He hesitated, and by time he went to speak again they were at the entrance to his lab, and she gestured to the door for him to enter.
"Go save the world."
*****
Natasha only had time to quickly grab a bite to eat before she found herself summoned once more. Banner's algorithm had found Loki extraordinarily fast, as it seemed like the villain wasn't hiding at all.
It turns out he was walking around in public, in Stuttgart, Germany. Rogers was already on route to intercept him before anyone else got hurt, and it was Natasha's job to provide a little back-up.
The situation was far from stable, as she soon found out. Cap was severely outgunned by the Asgardian, and with no clear shot she had felt pretty helpless during the encounter. Of course, that's when Stark made his dramatic entrance, taking over her PA system to blast out AC/DC's 'Shoot to Thrill' and taking down Loki in a single shot.
It was a little frustrating for Natasha, but at least they had apprehended him. In fact, it had been far easier than she thought it would be. Something about it just didn't feel right to the agent, and she felt nervous flying back to base, even when Loki was held securely.
Even the journey back, which should have been relatively simple, quickly went of the rails. The Black Widow was resigned to the quinjet as Thor and Iron Man fought over Loki, knowing that even Captain America's intervention had better odds of succeeding than anything she did. Knowing your limits was a talent, the way she saw it, and maybe the one thing Rogers was lacking.
Eventually they were brought back on board, leaving Natasha frustrated by her own lack of power over the situation. Thankfully, they managed to avoid having any more godly interruptions on the way back, settling for tense conversation as the men in the back eyed one another suspiciously - apart from Loki, who seemed to be suppressing a smile.
Once they arrived at the Helicarrier, Natasha made sure to accompany Loki and his staff onto the ship, not feeling too secure even with the armed escort. And like she expected, there was an incident along the way, though it was as confusing and unsettling as any of Loki's other actions.
As they came across a junction in the labyrinthine corridor system of the mobile base, they came to an abrupt halt. It was at this moment that Loki darted forward, breaking through his handcuffs and pushing through five men at an extraordinary speed to lunge for his sceptre.
Before the men had even recovered, Black Widow had raised her gun and cocked it. She held the gun inches away from the back of his head, and ordered him to "drop the sceptre."
This being the same man who just crashed a party to attack a guest with some sort of ocular device, before taking on a super soldier, he didn't react as she expected him to. He laughed quietly, then turned on the spot in an instant to face her.
She took a step back, still aiming her gun his way, a move mirrored by the fifteen men who were supposed to be guarding him. He looked her directly in the eyes and smiled. She noticed in the corner of her eye the head of the sceptre start to glow brighter, as he held it out to his side.
Glancing away from his stare for a moment, she looked to the blue gem, though no one else seemed distracted by the light. 'Was this an attack?' she thought to herself, before she was blinded by a brief and sharp flash.
In an instant it was gone, and she found herself in the same position, with Loki still facing her. No one, not even her, seemed to have moved during the tense encounter. He nodded, the smile gone from his face, and he placed the sceptre on the floor carefully.
"Many apoligies," he said, sounding almost polite. "I am not overly fond of bondage."
When no one made a move, he raised his hands above his head and said, "You'll see no more trouble from me - take me to my quarters, will you?"
*****
Once Loki was safely locked away, the Black Widow headed back to her quarters - partly to have quick shower and change - but mostly to calm herself a little. She was only just making sense of things, getting her rational drive back, when Loki had thrown a spanner in the works.