"And I… am… Iron Man."
All it takes is the simple motion of a snap to win. And that's what he does: he snaps his fingers. The Infinity Stones overwhelm him with all this power, the ability to do anything is too much for somebody like him. All he could think about was putting a stop to Thanos; all he could think about was protecting his family.
The flash blinds him, a loud 'clang' echoes in his ears. Only silence could be heard after that. The light was so blinding, much like when he first awoke in the cave… back in Afghanistan when he was kidnapped.
Searing pain holds his attention. His right side burns, but all he could think about was how he had gotten here. It all started back with that first Iron Man suit; the mk1.
Despite the fact he still couldn't see anything, he could feel his legs giving out. He stumbles a bit before collapsing down. Distantly, he could hear what sounded like one of his suits coming in for the landing. He doesn't acknowledge it, though: he was still trapped in memory lane. He remembered how it felt to almost die by poisoning, he remembered the fear that had taken over his body after the wormhole…
"Mr. Stark?"
He turns his head towards the source of the sound.
"Hey… Mr. Stark? Can you hear me? It's Peter. We won. Mr. Stark... We won, Mr. Stark. We won and you did it, sir. You did it."
Everything was still bright, but he could make out the blurry outline of Pete. Oh, how he admired his protege. Peter had to be the kindest person in existence. So pure… so in need of protecting. That's why he made the suits for the young hero… he couldn't mess up with the kiddo's safety.
He could faintly make out the warm body surrounding him. Maybe it was a hug… he was too out of it to really focus. The warmth was comforting, especially since his own body seemed to grow colder.
"I'm sorry... Tony…"
The warmth leaves him once again. Oh, how he missed it already. Breathing was getting harder and harder…
"Hey."
A new voice faintly swam up to his consciousness. Somewhere deep inside him, he was able to recognize it. Was it his lovely Pepper? He uses all his energy to look over and confirm his thought. His lovely, beautiful wife was right there with him. Oh, he should have been better to her. He should have done better to remember her allergy to strawberries… should have worried her less. With a strangled breath, he manages to whisper out a: "Hey, Pep…"
"Friday?"
"Life Functions Critical."
"Tony. Look at me."
His Pepper was smiling at him, eyes glistening, but she was smiling.
"We're gonna be okay. You can rest now."
With those final words, he takes his last breath. He thinks about his family: his lovely Pepper; his kiddo, Peter; his baby girl, Morgan; and his Rhodey Bear. With a final thought, he thought back to what Yinsin had said all those years ago:
You are a man who has everything, and nothing
Now he truly did have everything. The steady hum of his arc reactor dies out as he finally finds himself at peace.