That howl earned Gladio a low snarl as he veered out again, trying to get away from the intrusive presence of his partner. In the mixed up mind of his, he saw Gladio as a domineering threat right then and he didn't want to go back. He wanted to run, and keep running until his lungs burst and his legs gave out.

How dare he keep trying to rein him in?

If Gladio got close enough, he'd see that Ignis' teeth were bared in an unhappy snarl, and any closer and those same teeth would snap at him in annoyance.