Vaan "Ratsbane". Many people find him annoying, but I honestly can't help but love everything about him: he starts as a pretty childish boy who has to let go the Death of his Brother - who he is trying to not think about or else It makes him feel a great pain on the inside as shown
And well, when he kind of does, he understands that he doesn't have a place in the world - or to be more specific, he doesn't know what do with his life: he has been thinking so much about having Revenge against the empire and thinking about becoming a sky pirate that...he didn't do anything with his life. This is also why he decides to continue his journey with Ashe: he thinks that travelling with her, he will know what he can do in his life. And in a way, he was right: as the story progresses, Vaan becomes much more mature, finding not only his "supposed" place in the world(which is also the "dream" has been using to not think about his Brother, funnily enough), but in the semi-last dungeon of the game, Vaan finally breaks himself from the chains of Reks's Death and becomes free from his past, if I may say so. But Vaan doesn't have just his character arc for me: his relationships with the some members of the cast are also great as well:
- Balthier. with this skypirate, Vaan has an interesting pupil-master relationship(altough It's something that Balthier doesn't want to admit) and when Vaan becomes a real sky pirate in Balthier's eyes, he decides to give Strahl to Vaan if he was to die like The Leading Man he is, making it the "peak" of their pupil-master relation-ship.
- Basch: with this knight, Vaan initially doesn't have a great relation-ship and understandably so, after all
However, when Basch "defends" Reks from the other "knights" talking badly about his Brother, Vaan starts to see Basch in a different light: no more as an assassin, but more like...a father. Yes, Vaan slowly starts to grow fond of Basch, to the point that he later sees him more like a father, which is quite surprising, considiering how much Vaan hated him.
- Ashe: now, this is probably the most interesting one. Vaan and Ashe are quite similar: they both have lost someone dear to them at the hands of the Empire, both hate Basch and both want to get Revenge against the Empire. However, they don't really like each other initially: for Vaan, Ashe seems to be quite the selfish princess and, for Ashe, Vaan is more anoying than anything else, but - as you would expect - they get to know more about each other the more they travel together, with their friendship "flourishing" at Jahara and at the end of the game, where Vaan comforts her saying that she has now friends like him, Penelo and the others.
- Larsa: while It's true that penelo is his first friends, Vaan is undoubtedly the one he has the more interactions with. So, with Larsa, Vaan has a friendly relation-ship:
There would also be Penelo, but their relation-ship is just a generic "Childhood friends.jpeg" and becomes truly interesting only in Revenant Wings. One cool thing about them tough is that Vaan and Peneloare the opposite of each other, in terms of personality: Vaan can be rude, childish and unable to control his emotions while Penelo is calm, mature and knows how to act in different situations.
One last detail I like about Vaan is also how ignorant he is about Ivalice: he only knows about the deserts of Dalmasca and the Giza Plains, so the questions he does about the world of the game make sense and also help flesh out Ivalice herself.