Hrm...Let me take a crack at these.
Nakayama's EntryNakayama's entry and two of her friends, wanting to be more like the big kids, have formed their own "gang". Since they're just kids, though, their idea of what makes a rebellious youth group is a bit limited to harmless practical jokes. Ding-Dong Ditching, graffiti (drawn in chalk), prank calls, that kind of thing. When Barret runs into them, they've taken their "reign of terror" to the next level: dropping water balloons on people from rooftops. This understandably starts to annoy the townsfolk, so Barret takes action. This'd be the bit where the player learns to run up walls. He dashes up the side of the building, startles the kids, then gives them a scolding. Awed by Barret's coolness (dude just ran up a friggin' wall!), they go from being a bunch of wannabe delinquents to the Bright Bats' own personal fan-club.
Higurashi's EntryA lot of people seem to want this girl to be a digger, and I can see why. What if she was the receptionist at the Digger's Guild? If folks want to see her digging skills in action, then she could do a run of each digger-test course before the player does, to give 'em an idea of what they're dealing with.
Inafune's EntryShe really is the most out of place, isn't she? Like she's from some sort of Space Ranger anime or something. So, why don't we do just that? She could be the star of the latest, most popular kid's show "Lady Starforce"! Whether it's a cartoon or a sort of Power Rangers/Kamen Rider live-action thing is up for debate. I could see Pic and Nakayama's character being big fans of this show.
Itou's EntryGrill is the Bright Bats' mechanic, but who's the mechanic for Bullbreath's gang? How about her? Not only that, but what if Grill had a crush on her, despite their respective gangs hating each other? Ooo! Scandalous! ;D
Suetsugu's EntryI think back during the voting, someone remarked that they could see this girl coming from the Sart Farm. I can imagine she's none-too happy at Tron for stealing all her family's animals back in the day. I wonder what would happen if the Bonnes were to ever show their faces around her place again? Hm...
Of course the side-quest giver idea sounds great, too. What kind of side-quests would she give, though?
Ishikawa's EntryI could see her being a biker, like others have suggested, but...
Well, back when I had those fan-events in the Devroom, I kinda wanted her to run a pet store. One that had no pets. It would be the player's job to track down pets in out-of-the-way places to stock her store with (these pets would be some of the better entries from the Bright Bats mascot contest).
Yoshikawa's EntryThat last picture of her in the bottom left...it makes her look so mysterious, so shady...During the voting, I kept imagining her wandering the frozen wastes of the Forbidden Island (probably not the smartest thing for her to do, considering what little is under the cloak, but whatever). I can't for the life of me think of a REASON for her to be there, though (at least not a good one), so how about this instead?:
Shady cloak, eyes hidden behind goggles, but clothes that clearly wouldn't be worn by any sensible criminal. I'd say she's Teomo's resident information broker, and thus the source of most of Pic's info. The fact Pic doesn't get his info first hand could be played for some laughs.
She'd probably be a bit theatrical with the whole "mysterious information broker" angle, prone to flourishing her cape and "vanishing without a trace until she is needed again" (probably just by saying "look over there!" then being seen running away in the background, possibly tripping along the way.)
Kaji's EntryThis one's tough. She could fit in almost anywhere, so it's difficult to think of a solid character background for her other than "a townsperson". Hrm...
Barret doesn't seem like the type who likes reading. Maybe she could be a student doing some studying in the library? Since Barret's not about to pour through the ancient texts, drinking in world history, she could serve as a sort of surrogate reader, spouting off factoids of the world's past and other things she's read in her books.
Komaki's EntryWELP. I'm absolutely stumped on this one. Absolutely no idea what purpose she could serve in this game. Guess we can't use her. Oh well.
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And I think that's everybody! So, what do you guys think? Do I have anything worth keeping here?
Also, can someone fill me in on all this ComCap/YAG stuff?