Gladio's face sure does fall at that 'you're a pup', given that he's older than Noctis but more so because it's actually true. Why, as a wolf, he tends to act more immature he has no idea when real wolves grow more mature more quickly than a human, but it's frustratingly true. His lips thin in his displeasure, but he tries to soothe himself with the idea that if he hadn't been there last night, who knows what might have happened. Also, he wants to know what that man had in mind. Who he was after.

However, his whole series of thoughts gets derailed when Noctis suddenly lifts his shirt and turns to display the massive scar running across it.

He knows... a little. The information about what happened that night has been very hush-hush, not even Ignis willing to talk more about it. He knows there was a daemon attack and many had been killed, nearly Noctis as well. He knows Noctis had been hurt, badly, and had spent a great deal of time away getting healed.

But seeing it, the scar still pinked as it would take years to fade to white, is a very different reality than hearing about the terrible news some months back.

"...Noctis..." Quiet, not even sure what to say in the face of that reality.