He screams before he's even registering what's going on.
Tony feels his mouth open, feels the vibrations in his throat, but he doesn't hear it. He can't hear the screams he knows he's making, can't feel the floor as he falls to his knees in front of what is basically his sons body, doesn't hear the others calling to him.
Tony makes a whimpering noise as the scream dies off, tears building up and streaking down his cheeks, hands coming up and covering his mouth to clog that painful keening he's making.
He feels someone's arms around him, hears someone talking, but he can't focus in on the words, can only stare horrified at what JARVIS was at one point. He can only lean into his arms and sob his heart out, tears streaking across his face, staining into Bruce's shirt as he clings to him and sobs.
There's no body to hold, nothing to bury, just emptiness where there once was something, someone, and Tony wishes for once that he listened when JARVIS asked him about creating a body for him. He wishes so many things to change, and he cant, he can't go back and fix this, because his son is gone and nothing else matters in this world.
His sobs taper off slowly, turning to soft whimpers as he shakes in Bruce's arms, while the man shushes him carefully, rocking him slowly to try and calm him down, and Tony just feels... empty.
He hears the soft beep of a questioning DUM-E and before he can think, he wrenches himself away from Bruce, who doesn't fight it much to Tony's surprise, and flings himself around the bot, sobs tearing themselves from his throat anew.
Bruce stands behind him and starts talking but Tony can't hear him again, and DUM-E beeps sadly, camera pointed at JARVIS's remains and Tony lifts his hand to block the view, despite the uselessness of the gesture.
DUM-E has seen his brother's remains and Tony couldn't erase that memory no matter how much he wanted to.
So Tony clings. Cries himself out. And sits on DUM-E's base and watches with red ringed eyes as Bruce tears apart the group watching for assuming his son was nothing more than a few lines of code.
Slowly, Tony stands, distances himself from DUM-E, who beeps at him once sadly before turning and trundling back over to U and Butterfingers, and stares dead towards the group, giving nothing of his emotional state, which said it all.
"Ultron is going to pay."