These characters are not in the main party but they too are more and less powerful friends and foes with whom our hero interacts.

Al-Cid, the royal Casanova of the Rozarrian kingdom. He travels with a very precise female assistant while sporting what could be the latest highfashion of Ivalice. Al-Cid possesses many of Balthier's traits but is oh, so much more obvious in his action and speech. Everytime the Rozzarian heir comes into the frame our leading man gets irritated down to his bonemarrow. This isn't showed out loud but rather with quiet gestures... when Al-Cid kneels before princess Ashe, calling her "Dalmasca's desertbloom" right before kissing her hand, Balthier looks away while, as I imagine, giving off an annoyed sigh.
Could Balthier hold feelings for Ashe? Nothing is impossible. But the most logical explanation would be that Al-Cid simply steals the self-proclaimed protagonist's spotlight, when openly courting the princess making everyone stand and watch in wait.

Like Balthier himself and even more so, Larsa is very intelligent and wellinformed for being so young, only 12 years old. Despite his age everyone listens to him and takes the young Arcadian's attempts to aid them seriously.
Balthier has a hard time trusting Larsa in the beginning and stays very suspicious of his intentions, even when the kids lineage isn't yet known to the party, saying "Stay where I can keep an eye on you". Eventually I believe he comes around and admits that Larsa's desire for peace is pure. However as any child should, Larsa has a naive side to him... especially when it comes to his family and friends, which could very well remind Balthier alot of his younger self.