"Nothing that couldn't be healed."

Best to leave it at that. As far as he was concerned, Gladio didn't need to know what happened if he didn't remember it on his own. It was clear that he was already bothered by the idea of hurting someone. If he learned what had really happened, Ignis worried about how his guilt would affect him.

"What matters now is that you're back and on the road to recovery. Noctis has been worried."