Ignis should've expected that Prompto would bring it up. He should've done it first though and not let others do things he's responsible for. There was a plan of bringing it up after the trip, maybe with Gladio around to tell him as well but- this happened. "Did you know?" Ignis asks quietly.

He can see why he would try to stop him- out of worry or something along the lines. Especially because he has no eyesight in the future. "I suppose I tried to stop you because of my state..." the image of himself with scarred eyes flashes in his mind. Perhaps, there was a way deeper, personal reason, but that doesn't matter. "My powers to protect you at the time were extremely limited."

Pryna... Ignis still doesn't know why she showed him that. "A reason... I can't seem to find it." His hold on Noct only tightens. "If... if there is a reason for it then why... why can't I change it?" his voice breaks.

"...why can't I keep protecting you from everything?"