Tony had kept Nattie rather sheltered during her early years, he never let on how many threats he got because of the weapons he made or the bomb scares that happened almost regularly and neglected to tell her that Happy doubled as a bodyguard as well as a driver.
So Nattie never knew the true danger her brother's life could be in—something that Tony and Jarvis kept hidden as much as possible as she grew up and began her hobby of hacking.
By the time she was in her twenties, Nattie had been confident that she knew the danger Tony was in and was prepared to deal with. May of her twenty-fourth year of life dispelled her from that illusion.
She had completely broken-down when Tony was kidnapped and then presumed dead.
She had spent the first night he was home awake and watching him simply breathing—sure that if she fell asleep, she'd really be waking up and it being a dream, him being back was a dream.
If after he came back, they spent more time together—rarely not being in the same room as the other—and gave the other reassuring fleeting touches and hugs, well they didn't mind and that was their way with coping with what happened.
That was the first time the siblings courted with death.
When Nattie came home to show Tony her new streaks and found him without his arc reactor and Obie standing there coldly calm, she froze as ice filled her veins and squeezed her heart. She had been barely breathing—so struck by horror, fear and uselessness—and hadn't seen the blow coming.
Tony had felt something scream when he saw his sister fall, saw the man he had trusted step careless over her limp body, and the blood pooling around her head.
Something in him broke at the sight of her like that, and fiery determination filled his veins as he swore Obie would pay for hurting—possibly killing—his sister.
Nattie had been someone he knew he couldn't live without, knew that he would shatter if she didn't walk on the earth, unable to give him her beaming smile ever again. The same smile that had won Tony's heart when he had be prepared to hate the tiny little baby in his arms when he was a teenager.
And he knew that was why he had been reckless in his fight with Obie—part have him had been convinced she was dead or at least slowly dying and hadn't cared if he survived the fight or not.
By some miracle both of them survived though not without scars. Nattie would always carry the scar of Obie's hard blow to the side of her head and Tony's heart would always hold the scar of Obie's betrayal.
They had spent almost a week together, basking in the fact that the other was alive, and watching Disney movies while Nanny cooked them pizza and other comfort food. They slept in the private living room of Nattie's set room—neither could really stomach being in the room where they both could have died—and lay tangled up on the couch and covered in blankets.
That would be the second time the siblings courted death.
The three time had been drawn out and long. Poison was difficult to counter, especially when the thing that was poisoning you was also keeping you alive.
As Tony became more resigned and careless, Nattie became more frantic to find a cure.
Nattie had never hated the fact she disliked science and didn't have the same grasp of it as her brother then in those long months.
Nattie had been the only one that Tony had told, the only one that knew that he was slowly dying and the only one that could see that he was preparing for the end.
Nattie survived solely on painkillers, donuts and coffee in those months. She had lost weight and holed herself inside so her skin turned a pale shade that it hadn't been since she started school and was allowed outside.
They had barely been able to relax about the fact that Tony wasn't dying anymore before he was flying off to save everyone again.
The fourth time the siblings' courted death was kept secret from Tony.
It had happened when Nate went out on her first out-of-country-mission. A new type of stun-gun had stopped her heart and it was only because of Tasha's cool-mindedness and determination that Nate was alive.
She would always remember the disconnected feeling she felt as she fell to the ground—her mind still whirling though her heart had stopped—and the horrible feeling of cold numbness that crept up her limbs before Tasha was crouching over her, green eyes panicked though pale face calm, and began pounding her chest to restart her heart.
She would always remember how her vision briefly darkened—she had been sure she was dead—before she was shooting up with gasping breathes as her body shuddered in Tasha's strong and comforting arms.
When she got back to New York, she went straight to where Tony was directing the building of Stark Tower and just hugged him long and hard to his pleased bewilderment.
The next day a picture of them hugging would be in magazines and newspapers with the question of 'Is Tony Stark cheating on his CEO girlfriend, Miss Potts, with young genius Artist?'
The fifth and sixth time happen almost at the same time with Tony caught in the propellers of the helicarrier while Nate was free-falling from said helicarrier with the Hulk her only saving-grace.
The seventh time happened later that day when Tony died putting the missile through the portal and his heart was only restarted because of the sudden shock of Hulk's roar.
Those would be the first times that they didn't go to the other for comfort. Nate had Steve and Tony had Pepper now. But if they talked more over vid-chat or Tony and Pepper was suddenly over for dinner more, well neither Steve nor Pepper mentioned it.
The eighth time they court death was because of Killian and his AIM project. They were shoot at by missiles, their home destroyed before they were separated.
Nate went numb when Tony was once again presumed dead.
He had barely been home long before he was having once life-threating surgery, and part of Nate can't help but resented both Tony and Pepper for it. Pepper because she was the reason Tony was going through with it and Tony because he was using Extremis—which had only just be stabilized—so he would survive through it.
They comfort each other briefly, Nate climbing on his bed and resting her head on his chest like she had always done since she was little. But they didn't need to cling to each other as closely anymore, though both were pleased and relieved that they were back to living together even if there was more people living with them now.