Dear iiMKUltra,
You are the Jailer
While you may not be the one who hunts down the criminals in the Town, you’re the one who keeps them from continuing with their illicit activities once they have been apprehended. At least until their sentence can be carried out, anyway. But while spending a Night in a cell can be inconvenient, at least people are safe from worse things.
At Night, you may PM the host with “Night X - Lock up <user>.” <user> will be tossed into a cell for the Night. While inside the cell, he will not be able to perform his other Night actions, but he will also be protected from anyone trying to kill him. He will still be susceptible to other things, however. You may not lock up the same person on consecutive Nights, and you may never lock up yourself.
You are aligned with the Town.
You win when the Town is safe again.