Morozov, they know. I've come into a facsimile of the Fortune Teller's notes and... they know. Say the word and I can make the switch before sun-up.
ABILITY:
The Demon receives the information of one Townsfolk at night & may change it once per game, even if you are dead. You learn if this happens.
STORYTELLER NOTES:
Choose a Townsfolk at setup to be the Inside Man's "target"; if that player ever ceases to be a Townsfolk, choose a new player. Information that is "changed" should benefit the evil team as best as possible. If the Inside Man is dead when information is changed, they do not learn that it happened.
The Inside Man lets the Demon in on a Townsfolk's information, and gives the Demon the chance to change it at will.
Playing as the Inside Man
Whether you live or die, your ability is, if sober, in play, so unfortunately there's no way out of your predicament, short of being drunk, poisoned, or changed. If you feel it's safe to out, feel free to let people know you are the Inside Man, but of course, there is a danger of Godfathers or Fang Gus lurking, and announcing yourself to town may put you on their radar quickly.
Similarly, it may be beneficial to out when you have learned that something has been changed, as it may prompt town to question their information: this particular piece of information is always reliable!
Example
Joe is the Inside Man. on Night 4, he learns that the Demon has changed someone's information. The Fortune Teller, on that night, received a no, and few other information roles are still in play. Joe surmises the Fortune Teller's information for that night may have been corrupted.
Bluffing as the Inside Man
Did the Flowergirl get a "yes" that is damning for your Demon? Did the Town Crier figure out who the Evil Twin is? Is the Balloonist one more name away from pinning down the evil team? Not anymore! Let folks know that the Inside Man has done its damage on a night most convenient to your team, and, even if it comes at your expense, at least your team is safer for your confession.
It's also useful to note that you won't learn if information has changed if you're dead, so as a self-preserving measure, that may prove useful to give yourself a few more valuable days to act.
Example
Gabriella is the Counterfeiter bluffing as the Inside Man. They are nominated on Day 1, but claim to be the Inside Man, asking for clemency in the event the Demon chooses to use their ability. Town lets them live, and they gain full use of their ability, eventually dying on Day 4 - but only after claiming that information was switched on Night 4!
Jinxes
N/A.