[Katsuki will let go after Izuku complains about the pinching. Smiling wide now that he's sure that Izuku wasn't some kind of dream, or hallucination or hologram or who knows what else. He was so excited to see him here. He couldn't wait to show him all his new friends that he somehow managed to make on his own, and tell him about all the Quests and harrowing adventures he's been through. Show him all of his cool new powers, and talk about how awesome the two were and how their fights went during the war and what the future will look like after and---]

...m..my arm?

[Izuku looks so shocked at the sight of the amputated limb, and it snaps Katsuki right back into reality. Now that the two are standing and looking each other over properly, Izuku is getting a good look at all these injuries and he looks so worried. Katsuki's smile fades as Izuku reaches out towards the missing limb, and he notices how the boy's eyes begin to look wet.

And notices how he's missing a few scars that he should have.

That gets Katsuki's mind to start racing, and he realizes something he never even thought could be a possibility.]

Before I tell you, Deku. I need to ask you a question.

[If his hunch is right.... this might be a huge problem.]

What... what were you and I doing, before you got here?