Here's Cindy's story that we have seen so far, which I will follow with two points, both of which provoke tough, important questions: Cindy Chandler was an air hostess (or stewardess, if you prefer) aboard Oceanic 815. She gave Jack free vodka (!?) and tried to get Charlie out of the toilets just before the crash. She also somehow made a super-sprint from the fuselage to the tail-end whilst Oceanic 815 was crashing. How she got from being here. . .
. . . to being here. . .
. . . is pretty much summed up as an intentional mistake. When the creators decided to have the pilot be the man that the Black Smoke kills (after delivering the required information about Oceanic 815 losing communications and flying off-course) Cindy was surplus to requirements for the fuselage section. The tail section, however, needed someone to deliver the same information - and so Cindy was selected as the crew member that could inform the "tailies" that they had lost communications and veered a thousand miles off-course. Never mind the fact that she was at the front of the plane when it started crashing; put it down to creative licence.
With the tail-end survivors Cindy remained up until journeying with the group as Michael, Jin and Sawyer lead them to the fuselage side of the Island. En route, she was swiftly, silently taken by The Others. The next time we see her she has been somehow accepted into The Others; she tells Jack in his cage that they are "here to watch" and, later, is part of the pilgrimage of Others to the Temple.
This chain of events leads me to two open conclusions.
a) Cindy Chandler is a liar and was an Other all along. The big argument against this is compelling: if she was an Other then she willingly allowed herself to be in a plane crash that she could surely have had little guarantee of surviving. That, to me, is a MAJOR blight on the 'Cindy was always an Other' view.
On the flip-side, she claimed to be good with faces and yet didn't recall seeing either Jin, Michael or Sawyer on board Oceanic 815. There's an argument here that says she was covering for Goodwin when she made this claim. Also, the manner by which she was 'taken' by The Others; not a sound nor sight of the event. Maybe she wasn't taken at all. Maybe she just quickly slipped away. If her story isn't genuine she deserves to be considered alongside Libby and Rousseau as marginal characters with major question marks against them.
b) Cindy Chandler was a genuine stewardess that survived the crash and was taken by The Others and was quickly converted. This, to me, raises the question of how The Others could so quickly change her mind and make her pro-Other. Because if Cindy can be easily converted, then why not Jack? When Ben needed Jack "to want to want" to perform surgery on him, why not just indoctrinate him the way Cindy had been indoctrinated and make him pro-Other?
Is it because Cindy was on Jacob's list and Jack wasn't? Is that the nature of the list? It is those that are able to comprehend The Others' agenda and collective motivation? Those that are able to be converted and those that aren't?
What I think is this: Cindy Chandler's story is genuine. She was an air hostess. She survived the crash. She was taken by The Others because she was on the list. She became converted to the group. And this was because she, as a person, was 'resolved'. Unlike the other survivors not on the list, she has no issues to overcome, no redemption to seek, no history to reconcile. She was a tabula rasa, clean slate, ready and accepting.
She was there to watch. Not to BE watched.