God, to think this had all started with him bothering Pepper about the possibility of having a kid on the way before they (finally) got married.
Then came the stupid wizard and the trip through space and...
And now one of the kids in Tony's life was gone.
He didn't even have a clue as to whether or not the other had made it through Thanos's culling. And he was scared to find out if Harley made it or not. He'd just lost Peter right before his eyes. Bright-eyed, eager Peter clinging to him, scared to know that he was going to die. It wasn't even because Peter was Spider-man like Tony's pretty sure they were both expecting things to possibly end. There probably would have been some peace in going out being a hero, not this "oh, you lost the lotto, deal with it" deal.
Worse, there wasn't anything Tony could do, could have done to prevent it. Even if the kid had stayed on Earth like Tony told him to, the moment Thanos collected the stones, people were going to die regardless of where in the universe they were.
Damn it all!
Resources were finite, sure, but that wasn't an excuse for this! You learn to live within your means, and sometimes the limits have to be toed before you figure that out, but it could be done. Wiping out half of the universe's population was not a solution. It caused more problems, more deaths when the pillars of societies were removed at random for reasons unknown, when families were torn apart.
A thankful universe? They would all be cursing Thanos's name for the loss.
And Tony would be up near the top of the list, because this, this was worse than having another moon dropped on him.
7 billion people on Earth and he'd maybe saved 3.5 billion when his current best made the purple prick bleed a bit. And "current" was the key word here. Thanos had better have found a deep hole to "rest" in, because once Tony's done finding a way home and studying the tech left behind on this planet, getting as much alien tech and understanding of it as he can, Tony's going to build a suit that makes his current model look like the scraps the Mk.I was built out of.
Then he's going to complete his own "vision" and kill Thanos for "the good of the universe."
Author's Note
Just watched Infinity War today and damn the feels of how they lost! Strange had to have spared Tony for a reason if this was the path to the future where they "win" and being Tony, he's probably going to build an even more awesome suit to do it (though damn was the nanotech one cool). So yeah introspection, prediction, and feels because damn it, they killed Spidey!