Tony when he heard you scream.
Tony, you and the rest of the Avengers were fighting a battle. Everything was going pretty well until you got stabbed in the back by someone you didn't see coming.
When Tony heard a scream, he immediatly recognized it and stopped doing whatever he was doing. He looked in your direction and was shocked.
He made sure every enemy that was close to him or you got killed and he got to you.
"(Y/n), stay with me, please."
"That- looked smooth, Stark." you struggled a bit with speaking.
"Hold on, you're gonna make it!"
You didn't really understand why Tony had tears streaming down your face, you always thought you were just a collegue of his.
"(Y/n), I wanted to tell you something for a very long time and I never found a good moment and I assume now isn't the best moment either, but I like you, very much and I can't have you die, not now, not ever. So please, hold on and stay with me."
That explains the tears.
To be honest, ever since you met Tony you were always attracted to him, but you kind of forgot it because he never showed any interest in you. Until now, now all those feelings came back instantly.
"You just gave me a reason to hold on, Stark." you say quietly, smiling shyly.