Steve
The kid reminded him a lot like himself when he first left the SHIELD facility after being defrosted.
Lost, alone, shattered. His entire world had been ripped out from under his feet.
The kid had been through a lot, more war than even Steve; and was the only Avenger who'd ever fought in an actual war. All the Avengers had their share of demons; they've all fought in in their fair share of battles. But war is a different type of beast all together. One that Steve not only knew, but saw, that Percy Jackson was intimately acquainted with. He felt a flush of shame.
The Avengers had done this. They'd torn this kid away from his friends, from his family, from his life, to throw him headfirst back into some of his most painful memories as they ask him to guide them back into an unfamiliar battleground. All on his eighteenth birthday. Jesus, the Baby Avenger was barely an adult, and he came to visit fallen comrades. They watched as he brushed his hands over different grave markers, pausing to say something at over a dozen different headstones and memorial markers before stopping at his final destination. It was heartbreaking.
Steve peered closer at the grave markers Percy had stopped at. The dates on all of them were gut wrenching. Hardly any of them were older than twenty. None of them had reached twenty five. Percy and Nico had warned them that demigod life expectancy was low, but to see the proof of it in front of him... it made him sick.
He glanced over and knew Clint felt the same way. They'd become Avengers to protect the world. And it turns out that they were woefully under qualified to do so from some of it's most dangerous threats. Instead that burden had fallen on children. Children. Kids were saving the world from some of it's greatest threats, and nobody ever knew about it. He shook his head before quietly walking out of the cemetery to wait by the car. He wasn't going to intrude on the kid's privacy any longer.