He doesn't think twice about it. He probably should.
He doesn't know this yet, but this whole thing is going to cost him more than his life.
He knows he can't get the kid to safety in time when robots show up. His fatherly instincts take over, and he covers the child's body with his own. He knows his responsibility should be towards his family first, not some random kid in a country he's never been to before that day. But he's ready to sacrifice himself anyway because he's an avenger, a hero. But he's also someone who wants to redeem himself.
It's amazing how fast his brain can think when he's about to die. He remembers Laura, her smile and their wedding day. He remembers his son and daughter and their giggles whenever he comes home. He thinks of his unborn child and how he'll have to grow up without a father. But he's sure his teammates will support his family when he's gone. And so he thinks of Natasha, of how she will react to his death, but also of their missions and bickering and hospital stays and practical jokes on S.H.I.E.L.D.'s new recruits.
He should be dead by now. He heard the unmistakable sound of shots being fired. He definitely heard it, so close to him.
He looks up.
He wants to scream, but the words barely come out. "Nat...What did you do?!"
She's fallen on her knees in front of him, blood oozing from eight different gunshot wounds in her chest. He lays her down on the ground and cradles her head in his lap.
She smiles weakly at him, and he can't help but smile back. She struggles to say something, and he wonders if the struggle is physical or emotional. She finally speaks, stuttering in the process, "I've always loved you Clint. More than a friend."
He doesn't know how to respond to a dying confession, and all he can think about saying is, "I thought love was for children."
She smiles again, but she doesn't reply. A few seconds later, her chest stops rising. Her muscles relax, so her smile disappears. He lets out a scream so loud, so alarming that everyone freezes to look at him. He holds her corpse as tightly and closely as he can, and tears stream freely down his cheeks. He doesn't care if people stare or if someone mistakes this as a weakness.
Natasha Romanoff is not a weakness, she never was. She was always his light even though she was more messed up than he was. She was his best friend, his support, his partner, his confidant, his source of happiness. She was the most important woman - no, person - in his life, right there with his wife.
It's funny how before dying, his mind was so quick to think, but when the person he holds dearest to his heart dies, his mind can't process anything anymore. He knows she's gone for good, yet he doesn't believe it. He knows he should get out of the flying death trap, but he can't control his body anymore. He registers hands pulling him to a ship for safety, but he's so busy holding on to Natasha like she might slip away that he doesn't know whose hands they are.
He hears the explosion of the fallen city in the distance, but it's merely background noise to his cries. He doesn't know how long it takes, but eventually, they're at some place his teammates deemed as "safe". Someone tries to pull him away from Natasha, but he's holding on to her for dear life, as if if he transmits heat from his body to her slowly cooling one, she could come back to life.
But she doesn't.
She never will.
He blames Tony at first, says he was the one who created Ultron who created robots who shot Natasha. He doesn't - can't - say killed. He's not accepted that yet. But then he realizes something he wishes he never did. He is the one who killed her. Robots shot her, but he is the one who killed her. He is the one who didn't think about the consequences of rushing to his death and left her to think about them for him, like she always does. He left her to clean up his mess, and she did. But she's the one who payed the price.
His usual weeping then intensifies, and guilt starts eating away at him.
He cries himself to sleep, wondering how Fate could be so cruel as to take her away from him. But he can see her again when he falls asleep. Sometimes, it's the good old days, when they would go on missions together, when they would annoy each other, when they would train together, talk together, eat together, have fun together. Other times, and those were the most frequent, he would see her die in his arms over and over again until he woke up screaming, or he would see her blaming him for her death until he woke up crying.
He barely reacts to what happens around him. It's like he's totally numb. He nods when people ask him if he's OK - though he's far from OK - and spends his days training, looking for a way to let out his frustration and sadness. Because it should have been him, not her. Not her. And sometimes, he breaks down crying in the middle of hitting a training dummy and finds himself rocking back and forth, singing the Russian lullaby she always sang to him after bad missions.
He stops eating. He loses 9 kg in 20 days - something girls would kill for. Eventually, his wife calls in his teammates to the rescue, and they force some food into his mouth.
After a couple of months, he stops crying. But it's not because he's moved on, it's because he's pretty sure he used up all of the liquid in his body. Everyone was surprised that Clinton Francis Barton cried that much. He was surprised that he could cry that much. But it's Natasha Romanoff that we're talking about after all, and she's always had a way of making him do shitty things.
She sacrificed her life so that he could live. But he doesn't want to. He doesn't want to live in a world without her, in a world so cold without her touch, so dark without her light.
Because in that mission, he didn't lose his life. He lost something far more important; he lost his soul when he lost her.
However, slowly, he moves on. But he doesn't forget. He'll never forget. Everyday, he still misses her. Everyday he's not on a mission, he brings flowers to the grave that has a tombstone engraved with the words "Natasha Romanoff. Hero." Sometimes, he even brings his kids with him to say hello to Auntie Nat. And whenever he can, he tells them the story of a wonderful redhead spy that saves the life of her idiot best friend.
He wonders if her love was unrequited. But he realizes that it wasn't. That he loved her to death. Apparently, that has a literal meaning now.
And he'll love her even after they're both dead.