He knows he should be reasonable. He also knows that by now Gladio knows he made a mistake. But Ignis is seeing red and wasn't going to sugarcoat it at all with him. Especially because Iris disappeared.

"What in Six bloody hells were you thinking!?" he hisses out. Then he does what he almost never does- raise his voice. "Tell me! You Shield to the King! Tell me how does one just ups and leaves without a trace! Leaving everyone and everything behind, especially the King he's sworn to protect?!"

And in his rage, Ignis doesn't even notice when he closed the distance between the two of them and grabbed Gladio by the shirt with both hands.

"YOU TWO COULD HAVE BOTH DISAPPEARED!"

The same way Iris did.