You ever wonder why we're here?
My bet is that every character has a reason that they specifically were taken here, and not just because they bought Wagstaff's inventions. Some characters have a personal connection to Maxwell/Charlie/Wagstaff, but others... not so much.
Wilson:
Willow:
This is an interesting one. We saw in "From the Ashes" that a terrorbeak tried to kill her as a child, probably before Maxwell even had the book. She also has Bernie, seemingly the only thing They fear. No idea what They want with Willow, or why her toy bear is/is possessed by some powerful magic entity.
Wolfgang:
Wolfgang was in the circus that caused the train crash, in which Maxwell found the Codex Umbra. My guess is that if the Codex belonged to the circus, maybe Wolfgang knew something about it.
Wendy:
She was related to Maxwell, and given the scratches on every photo of William, I would assume They wanted to tie up any loose ends. Alternativly, whatever Abigail's flower is could have something to do with things.
WX-78:
My guess is that this was a mistake. I think WX was just a test, thrown into the portal because his morality module or something was broken. Wagstaff never thought he'd see him again, so I'd say he was the crash test dummy.
Wickerbottom:
We have very little to go off of, but we do know she's magicly inclined. They could have targeted her because of what she knew.
Woodie:
Wes:
Because he secretly knows what They're planning and how to stop them.
Maxwell:
Wagstaff:
Wigfrid:
Maybe in a past role, Wigfrid knew Charlie? They both were in show business, so they may have met.
Webber:
I think Webber was another accident. I don't think that someone like him would have been able to build the portal. My guess is that he found someone else's portal some how. It would be pretty cool to see Webber's father or someone close to him build a portal, only for their small child/relative to stumble in.
Winona:
While she does have a direct connection to Charlie, she wasn't chosen to build the portal. She was never tricked by Maxwell. Winona was a variable They forgot to take into account.
Warly:
Not much to goo off of, but I have an idea with little evidence. Warly was a worker on a ship of some kind, so what if he was on the RMS Celtic with Maxwell? Perhaps he had some influence over Maxwell decision to become a magician?
Wortox:
Wormwood:
Wurt:
Pugna:
Skin trader:
Lot's of people think he's Jack. Not really anything else to say.