ooo yeah. very different phrasing there. and very fitting.
In short, what I think...
tony "gets to" become complete when he loses his life because his death, the one he always knew would happen in his suit, the one hes been preparing for since he first glimpsed space, the one he knew was coming... his death was full circle. His death wasn't something where he left a million projects, where he went into the battle expecting to make it out, only to suprise himself with a death that he knew was coming ut wasn't ready for once his happened. He gets to be complete. His life gets to end in a satisfying way, one where his death mattered. One where he gets to rest, really rest, his death is one that signifies its all finally over. He dosn't die before peace is achieved. As the peace settles over the world, his body hits the floor with it. He rose, as iron man, to create peace... and he falls, once he fullfuls that purpose. He gets to be complete. He does what he wanted to do, and his life ends on that completeness. He checks off the box on his to do list and dies in the next moment.
Its something he never expected, something he never believed he would get. To get to see his lifes work, to get to see a moment in which there is no more grave threat. To get to see everyone believe him, that the danger he always saw was real, and to get to never see another danger rise and take its place. He never thought he would get it. His death is a reward. Its a sleep after a long day, where the last task you complete is one youve been trying to do for years.
Tony's death is the sleep after your disertation gets accepted, and its all over. you can rest now. you get to sleep.
Steve becomes complete when he gets [a life] because, while Tonys defining trait was that he was so sure he would lose his life meaninglessly (and hes terrified of that), Steves defining trait is that he is sure he wil never get to live for just himself. He has been a soldier for so long, always fighting for another, always fighting for the right cause and doing right by other peoples goals... he chooses which goals to align with, absolutely, but his suffering and happiness and all that, its never Exclusively His. He is happy because other people get to be happy. He is sad because other people are upset. He doesn’t get the luxury of insight and expression as to his own emotions and goals. He is a soldier - he's there to work towards someone else's freedom, someone else's liberty. His failures and successes are not his own. His life dosn't belong to himself.
Until, he goes back in time. He, presumably, lives a life in which he lives for himself. He makes his own choices. He works toward his own goals.
Steve's completion isn't a moment. Its not like Tony, where the curtains close with his eyelids, and he is left thinking that he did it, and its done. Steves completion of his life, steves satisfaction that he did it, comes with every moment in which he works for his own reasons. Every moment he gets the luxury of choosing something for himself, and setting aside group goals.
Steve becomes complete. Its a process. Baby steps at first, practicing that authority over his own life that hes not used to. Slowly getting better at it. Its a process, there is no curtain call with Steves becoming. He simply... becomes complete. He becomes himself. He becomes a person with a life, with every day. Its a process that Steve allows himself, rather than a reward he is given.
If Tony's death, Tony's "getting to become complete" is the sleep a doctor gets after their dissertation has been accepted, then Steve's life of "becoming complete" is the fretful sleep a writer gets when they have a good idea, writing down more concepts every time they wake. The book, Steve's life, becomes complete. Its messy. Its confusing. And its slowly becoming solidified, piece by piece. And sometimes Steve thinks it'll never be complete, and that dosn't bother him much, because its not the being complete he wants. its the becoming.
