Natasha's is a in a little different style than the others. Hers was actually the first one I wrote, and I was still trying to find the right way to write it. I decided I liked this way though, so I left it.
As always, read, review, and (most importantly) enjoy!
Natasha had worked with Stark for several months before the rest of the team had even met him. She had dealt with his egotistical, child-like ways and learned how to handle him. Still, Natasha had a calculating mind, and she began to notice things about Stark that she wondered if the rest of the team had picked up.
Stark hated thunderstorms. Without fail, no matter the where they were stationed, she would find him in his lab, some classic rock band screaming loudly, immersed in some new project. If the storms came at night, he would get up and go down to his lab. He claimed that he was a light sleeper, but Natasha knew from personal experience that he slept like the dead when he found his way to a bed. She wasn't sure how he always got such advanced notice about the storms, but she figured Jarvis could be very accommodating. When he didn't catch them in time, well, she had never seen him leave a room so quickly or so silently.
(She finally figured out that the lightning reminded him of the flash of a bomb, and the thunder reminded him of the many explosions in Afghanistan. The moment of realization had happened when she was walking past Pepper and Stark's room during a storm one night and she had heard Pepper's voice, mostly calm but with a twinge of sadness in it. Tony, come on, breathe. It's okay, I'm here. You're here. They can't get to you anymore.)
Along the same line, Stark hated standing water. It's not that he avoided it, because really, that was pretty much impossible when 80% of the world was made up of the stuff. He was certainly wary of it, and between the choice of land and water, he always chose land. His famous suit checks became more pronounced when he had to fly over water and he always chose to fly by himself, rather than in the jet.
(There was a pool in the Avengers' Tower, one that rested on the edge of the building so that the swimmer could look out over the city. Clint and Dr. Banner had decided to just relax one day, and spend the whole day at the pool. Somehow they convinced her to join in with them. They had Jarvis call Stark up, figuring that if anyone wanted to party, it would be him. When he appeared on the deck, he had eyed the water first before turning his attention to his teammates. The decline to party with them had been polite but the smile and banter had been forced. Natasha recognized the look in his eyes—she had seen it in the undercover agents' eyes who had returned from a mission gone wrong. Post-traumatic stress, the psych department called it. Natasha called it an unhealthy attachment to memories.)
Stark literally did not know how to take care of himself. When she had first agreed to work for him (and by she agreed, she means Fury knew he would offer her the job and she had been ordered to accept it), she had thought that Pepper's instructions were a bit over the top. Remind him to eat, then order him something and place it in front of him a half hour later. Who needed reminding to eat? And then she had spent her first day at the house with him and discovered that Tony Stark needed someone to tell him to eat. And sleep. And shower. And, in general, live his life. He was better about it when there were others around, but sometimes Natasha still found herself bringing him food and carting him off to bed.
(Natasha remembers one time they had gotten halfway through a briefing before they noticed it was too quiet. She was sent to find Stark, but she already knew where to go. Sure enough, he was in his lab, working on new modifications for the Iron Man suit, pinging ideas off of Jarvis at the speed of light. There were dark circles under his eyes and cups of coffee littered all over the lab. When asked the last time he had eaten and slept, he gave the answers of a day and three days respectively. Yet he was looking at her like she was the insane one when she ordered his ass to bed.)
She won't deny that Stark is intelligent. She might even go so far as to say that he's a genius. But she does know that he constantly has ideas running in his head, calculations for flight trajectories, designs for more controllable flight stabilizers, even just new layouts for his workshop that would make moving around a lot more efficient. She thinks this is what contributes to his inability to take care of himself. Sometimes she wonders if he really does have a normal attention span, but he holds the thoughts of six people and that's why he can never stay focused. She can tell when he's trying to force his thoughts to slow down so he can pay attention. Maybe that's why she prefers Iron Man to Tony Stark—Iron Man needs to have the ability to process six different thoughts at one time, but Tony Stark could do without such abilities.
(She remembers being in the middle of a briefing, mildly distracted by the sketch Stark was doodling on an almost invisible screen. She wondered if he was trying to hide it from Fury, but she doubted it; it wasn't Stark's style. Then, he just stood up and left, leaving his doodle behind. Later, when Natasha found him, she offered him the design and asked if he needed it, he looked like he had forgotten all about it. Which, in fact, he had. Instead of inspiration on the project he had been drawing, he had made a sudden breakthrough on a completely unrelated project.)
Natasha knew Stark was paranoid. It really didn't take much to realize that. He had trust issues, but anyone could relate that back to being betrayed by the closest thing he really had to a father. He guarded all his designs fiercely, especially his military and weapon designs, but there was a reason the arc reactor was in his chest. What was harder to see was that he didn't always trust himself. She thinks it's why he's always preferred to be alone, because when he's alone nobody else's emotions, thoughts, lives are his responsibility. There was just him, and he didn't have enough self-respect to really care about what he did to himself. But that was before, before he had a relationship and a team to look after. And now she knows he struggles every day with their company, even though it was him who asked them there. She sees this.
(She saw this when he told them where the arc reactors were, and how to use them. She saw the back up plans and theories and safety precautions running through his eyes. If it was up to him, they would never know how to save his life. But there is one person that Stark has never been able to resist and she knows it's for Pepper that he does tell them.)