Alright, taking that little story and getting it more into an actual character idea, here we go:
Crown Cork, Earth Pony, son to the Cork bottled drink "empire" (as far as pony businesses can be called empires), whose main talent is painting the pictures that go on the bottlecaps. As the story says, he was previously groomed to be the successor to the family business, before he discovered his talent. Ever since then, the topic of who would succeed his father never really came up, though he always meant to talk to him about it. Right before the campaign start, he and his father are on a business trip to Canterlot where his dad was planning on making a "big announcement". Figuring it was about who would take over the business in his stead, Crown promised himself to talk about it. Naturally, he never gets the chance before the adventure starts. In addition to his family and his business, he'd also have a special somepony of several months; the daughter of one of the farmers they get strawberries from for their sodas.
The main concept of the character is that he's very much like a noble; used to being recognized, used to having money, not terribly used to physical hardship and trouble. While the Corks don't actually have a noble title, their sodas are at least known throughout the whole of Equestria. If your last name is Cork, it's good odds ponies have a decent idea of who you are. The Cork family is also known for being hard-working, however, the soda business isn't exactly a physically demanding job. So while he may be used to staying up all night trying to balance the books, a day of rough hiking is new to him.
I know it seems like I'm just listing traits and occupation stuff, but a lot of the character is already there in my head. I just need to get it down on paper. I haven't quite done the word association bit, so some of this might change, but I did have a few thoughts for the group so far:
Ravian: Here's a thought; how would you like Soot to be Cork's go-to errand runner? The guy keeps pretty busy, and the family isn't into keeping personal servants, so it's not too far-fetched that he'll need somepony to get him things. To further add hilarity to it, he could be completely in the dark about her thieving ways. This time, it could be that his special somepony requested something from Canterlot, and he wanted to spend all day with his father, thus he needs Soot to go get it for him.
Balmas: Best I can figure; the Cork family might contract Dive Bomb out for chemicals used in their soda-making business, and he and Crown have at least met professionally.
One Tin Pony: Same sorta deal, only Grease is contracted out to fix their soda-making equipment.
Diego: Crown would go to Canterlot often enough that it wouldn't be too far-fetched if he knew some of the tour guides by name.
(I suppose this mess means that, yes, I am formally interested in a spot in this. Five people in the party may not be such a bad thing, as that still leaves us with four should somepony find they can't keep up with this.)