The first thing you notice about this wiry young man is the golden haze - the *glow* - surrounding him. It sparkles in his eyes and gives his easy grin a warmth that you can *feel* right down to your gut. Erritis is a hero because he believes himself to be so. The more heroic his actions, the more powerful and self-fulfilling they become.
Erritis is found in Cliff's Edge, by the crashed airship. You can talk to him and mention that you're the falling star to get his loyalty. If you have Tybir in your party, he will stat conning Erritis into shin poisoning.