The Ever-Important Role
Erole is Gran's tactician, on loan to Nalavale when he's first introduced in the game. He's very good at what he does, although his methods (and response to his own methods) can be unusual. He seems to be very smart, but this is probably a given since you can't have a stupid (successful) tactician.
The name of Erole's theme is ' 愚者を夢見る少年 ' (gusha o yumemiru shounen), and is typically translated 'The Fool and the Dreaming Boy'. This is likely a reference to Erole's quote about "a 'fool' that never stops smiling even when they are sad".