The characters who team up in this group are a train conductor (Claude), a guy who tends to run off on his own due to a lack of Trust in Ark (Vanrose) and his maybe girlfriend (Shelley). In the final dungeon, with you controlling Vanrose, they take the first path and face a giant lizard that throws Red Eye (the undefeatable CIMA that you use to hold down switches) recolorings at you. Because on my first playthrough I forgot to equip Potion Bs and did the fight with little effort, Vanrose being stronger than Ark by a point and some of Shelley's comments throughout the game, I ended up dubbing them Team Awesome.
I'll cover Claude first since he really has not much worth mentioning. All you know about him is that he is the conductor for the Blue Creek, the train you're riding on. Since he's the last person you save and the game herds you into the final dungeon after beating Elvira, you don't get to have a chance to do some decent Trust farming, and he has no Trust conversation chain. It also doesn't help that most of his lines after you rescue him are about leaving the train to him, just worded differently. Poor guy's really shafted in character development as a result.
Vanrose, on the other hand, is pretty vital to the plot. As the leader of the pioneers, he finds it hard to trust a mere trainee, and that feeling only intensifies when Ark tries to obey Jester and get the group to safety, since Vanrose wants to go rescue Jester instead. He runs off on his own a grand total of three times, four if you count when he and Rick rush to save Diana, causing Ark to have to find and/or rescue him each time. But in the end, he finally admits that Ark is a good leader.
While Shelley doesn't get as much character development as Vanrose, she tends to make up for it with her calm handling of situations. She's told Vanrose off once or twice over how he complains about Ark, knowing it isn't helping their cause. During the time Vanrose decided to split into two groups so he could take the "easy" path, she goes with him in order to "protect him" (probably from his own attitude). And when Diana is mad at Rick and flirting with Vanrose and Ark to make him shape up, Shelley spends the duration trying to keep her under control, always seeming to know what the other girl is thinking. Plus, she wields a cool rifle.
As far as interpersonal relationships within the group go, there are a few. Vanrose and Shelley are good friends with Rick and Diana, and some speculate that the two of them are an item as well. Early on, I joked that Vanrose and Doug had formed a "Rag on Ark" club due to the two being the ones with the lowest base Trust along with reasons to dislike him. And you could theoretically mirror Vanrose and Shelley with Ark and Ivy due to their similar weapon styles (ninja-like blade & rifle vs. broadsword and gun).
All ages taken from the Character Books in the Blue Creek from both CIMA: The Enemy and Frontier Stories. Starting Trust is the Trust held by the pioneers at Game Start/After Jester's Death.
*Though Vanrose's age is listed as 31 in the game itself, his listed age in the instruction manual is 32. I'm considering the game ages to be the correct ones here, but am making a note of the discrepancy.