Hard to say, since they're still pretty early on in their adventure.
The naive, energetic teenage Human Swashbuckler girl just looks up to the others. She tends to chat with any NPCs, or help the Small members of the party with reaching tall things.
The Halfling Kineticist (Wood Element) is a young man who likes to whittle and whistle, and is glad to talk and tell stories to the Swashbuckler. He's glad to be in a group with other Smalls, and just generally chipper overall, despite being a farm boy with a mild bit of social anxiety amongst large crowds.
Of the two Ratfolk girls, the first is a Veeky Forums musclegirl Unchained Monk who spends much of her free time doing push-ups and crunches and showing off her guns. She grew up in a big, human-dominant city, and is eager to explore. She's got a thing for nice-looking clothing, and she really appreciates the floral aesthetic that the Kineticist maintains, what with the petals and buds that he's always got nestled into his hair.
The other Ratfolk girl is a stern, dutiful Witchguard Ranger. She appreciates the rest of her party, and is glad to help protect them as she can. She gets along with the Kineticist quite well, both being Small and both having an affinity with plants. She also enjoys the company of the other Ratfolk, despite growing up in a different culture amongst Elves. Helps to have one of your own around, y'know?
The middle-aged Human Cleric is like that one older friend you have. The one who has seen a lot of things and has plenty of advice to give out. He's also pretty well-learned from working in a Church for the last twenty years, and equally horny for the same reason. Now that he's out and about, he enjoys the return to his the lustful ways of his youth, and most likely has plans to screw every female member of the party, with the exception of the Swashbuckler. He's got a bastard son older than her, for Pelor's sake.
They seem like an odd bunch, but they like each other just fine.