Alphinaud's character development is wild. He rolls into Eorzea so fucking cocky. He's the grandson of the great Louisoix. He's 16 and he's a prodigy and he's going to fix the world. He has all these lofty ambitions and he knows exactly how to make the world better. He's playing chess with the city states in his mind. He's the main character in his own mind. He's the hero.
And rides this high of being this brilliant hero, savior of the realm, right up until it all blows up in his face. The blade of the sword he was brandishing points right back at him and all of his friends. Everything he worked so hard for becomes his downfall, and sets all his dreams back.
And now he's so mild. He's learned his lesson the hard way and he's probably terrified of every making that mistake again. He fully relies on his friends, consulting every decision with them. He still wants the best for the world, but he no longer sees himself as the main character. He is still smart, still a prodigy, but he's not the cocky brat he was when he first came to town.