Honestly, this was kind of the sight Prompto hoped for when he quietly opened the door. It was why he didn't text Gladio back or anything, just immediately changed his direction to go save Noct. Like literally save him, if the expression Noctis gave him afterwards was anything to go by.

He grinned at the pair, and since he was kind of hoping for this, he had his camera half lifted for a shot. It didn't take much effort or time to finish aiming it and snap the pic. Of course the resulting picture wouldn't be seen by anyone outside of this room, but it would definitely be one of his favorites, along with all the other candid shots he'd took of the other three.

He didn't say anything to Noctis. No 'see, told you,' even as he had admitted to the king what he'd hoped to walk in on. He just continued to watch them and wondered when they'd notice.