A/N: I am in love with Steve and Natasha's relationship. Not as romantic interests for each other, but as partners. I think I saw someone use the phrase "platonic soulmates" somewhere, and I can't think of a better way to describe them. I think they are one of (if not the) most underrated friendships in the MCU. Since 2014 (and you could arguably say even before that), through the fall of SHIELD, the training of the New Avengers post Ultron, the Avengers splitting, two years of exile, Thanos, and all that happened after that, they've stood right there with each other. I was really glad that we got to have more time with them at the beginning of Endgame, but I still felt like they just scratched the surface of their bond, so I was inspired to write something about it. It came out... much much sadder than I initially had in mind, but hey, we're dealing with Infinity War here, what can I expect? I'm hoping that this will turn into a collection of Steve-Natasha scenes, but I don't have any others written, so right now I'm considering this complete.

The title comes from the Greek word for brotherly love, and translated means "Love and Sorrow".

Thanos had happened, and it had taken Natasha less than two minutes to think of Clint. Or more generally, to think of the Bartons. Of Clint and Laura, Cooper and Lila, and little Nate.

It had taken her less than two hours to call Barton, but cell towers were down and satellites weren't functioning and the three and a half billion people left on earth were all trying to call the other three and a half billion at once.

It had taken her less than two days to come tearing down a gravel driveway in rural Iowa and jump out of her vehicle almost before it had stopped, nearly ripping the porch door from its hinges in her frantic dash into the house.

It had taken Steve less than two weeks to leave the whole horrible situation in Bruce and Rhodey's hands and come look for her.

As he rumbled towards the house, Steve noticed Natasha's jeep – the one she had all but stolen from the Avengers compound ten days ago – sitting not ten feet from the side porch, its driver's door still open. He wondered if she had turned the car off or if it had simply burnt all of its gas by now.

He slowed to a stop by the barn and turned his own engine off, climbing out of the car and shutting the door before stopping to listen. It was so quiet. Not only half the people, but half the birds, half the squirrels, half of all the animals were gone, and it made the world eerily quiet. His footsteps were almost painfully loud. Well at least he wouldn't startle her.

He knew better than to call out for her, she wasn't going to answer. If there was one thing he had learned about Natasha over the years it was that she never gave herself away easily. You had to look for her and really mean it before she would let herself be seen. So he looked. It took him a while – Barton had made no shortage of nooks and crannies for hiding in – but he found her eventually in the very top of the house, looking out at the road from one of the dormers in the attic. She stood with her back to him, arms crossed and hunched in on herself defensively, so he stopped in the doorway and waited to be invited in. Finally she spoke, her voice rough.

"They're all gone, Steve. All of them."

"I know."

And there really wasn't anything else he could say.

She turned slightly, though she was still watching out the window, and Steve took that as his cue. He stepped toward her and he reached out his hand, but stopped himself, hesitant for the first time in years. She was so fragile right now. He was almost afraid she would shatter if he touched her, and he really didn't know if he could fix her right now.

Thankfully, he didn't have to make the decision, as Natasha turned fully towards him and buried her face in her hands, curling forward until her head touched Steve's chest. He wrapped his arms around her shoulders, a little bit awkward at first – as she had been at Peggy's funeral – but firm, letting her know in no uncertain terms that he was there, and she could let go now.

Natasha cried. Really, truly, honestly cried. And Steve let her.

Steve's mind wandered, trying to find something, anything, that could bring comfort, but every thought that came sounded hollow and cheap. There was no silver lining to this. The enormity of their failure pressed down on him in a suffocating weight, and he realized that tears were slipping down his own cheeks as Natasha shuddered and keened. Squeezing his eyes shut, he held her tighter and bowed his head over hers.

They stood there while the shadows lengthened outside. As afternoon turned into evening Natasha's sobs slowed and Steve's tears dried. As evening turned into night, Steve remembered why he had come to the farm in the first place.

"We have to go." She didn't give any kind of response. He finally pulled back from her enough to see that her eyes were closed. Who knew how long she had been without sleep; he didn't even know when the last time he had slept was.

If it had been anyone else he would have simply picked her up and carried her to the car, but he knew Natasha, and even in this state she wouldn't want that, so he gave her a little shake.

"Tasha."

Her eyes snapped open, swollen, bloodshot, and defiant. "No."

"We can't stay here."

"I. said. No," she growled in a challenge, even as she let him keep his arms around her. Steve didn't have it in him to fight her on this tonight, so he just nodded and released her.

They went back downstairs, Natasha taking up residence in a corner of the couch which faced the door, and Steve sitting next to her. He gave her some space, but still made it very clear that he wasn't going anywhere. Minutes stretched into hours, and slowly but surely Natasha shifted closer to him until she was asleep with her head against his arm. Steve didn't move or try to cover her with a blanket, he just kept her vigil for her, always watching the door, always listening for footsteps.

There weren't any silver linings to this, he knew that, but he thought that maybe there was one mercy. There was one ray of light that had managed to survive these heavy black clouds: he still had Natasha, and she still had him.