Paine shows genuine enthusiasm for exactly two sidequests in the whole game, and they're both in this chapter -- the Via Infinito and the battle tournament with the Youth League. The latter I can only assume is a desire for some good old fashioned sparring. Then again, when Lucil makes her big speech about the goal of a Spira where no one will ever have to fight, Paine applauds. I've also noted that she seems much more relaxed and comfortable with her teammates in this chapter, especially as compared to the beginning of the game. Joking with Rikku and prodding her for gossip in Luca, gently teasing Yuna in Bevelle, smiling more often in general. Actual character development in a video game! I know this is neither the first time, nor the last, but it's still interesting to note it here.
The other thing that caught my attention: the first Unsent in the Via Infinito is Maester Kinoc. When YRP sees him, it's not Yuna who draws her weapon and cries his name in horror. It's Paine. This isn't exactly surprising, given her backstory, but it's a clue that I don't remember noticing before. Of course, it's been a long time since I fought through the Via Infinito. So far, so good -- I've only died and lost a bunch of levels once, and I'm on Level 45 (it did take me several tries to get past the Black Elemental). We'll see if I can keep it up in the increasingly difficult depths. This is the one sidequest that I am determined to finish. I've never gotten to the last level before. I will find a way.