Everyone that day saw something different.
Mikoto saw the start of new bond being formed between her two boys and couldn't be happier.
Fugaku didn't see anything but Itachi, who would carry future of their clan.
Itachi, as was expected of him, saw everything and beyond. He took one look at the absurdly cheerful expression on his otouto's face and knew it was he that Itachi had been waiting for. Sasuke was his chance. To escape, to love, to rise higher than the brightest flame, and when he couldn't fly any higher…To die.
Itachi, though young was by no means simple, saw all of this and nodded once to himself. It was decided. Itachi looked at Sasuke, who knew without a doubt that Itachi was the only one ever saw him clearly.
And Sasuke…. Itachi was curious what Sasuke saw when he looked at him in turn. Maybe, Itachi speculated, Sasuke saw him, too.