The Adventure Seed
You are visiting a small New England town and you see a curious sight: there is a dirty, unshaven man dressed in ratty clothes chained to the Stocks in the town square. But this form of punishment hasn't been used since Colonial times. No one in the town seems to pay much attention to him. He will tell you that his name is Zedekiah Brown and that he's in the stocks for the crime of Public Drunkenness, and from his breath and rambling speech you can well believe it; but no one will be able to tell you exactly when he was sentenced and how long he is supposed to stay there. The townsfolk just ignore him, as if he doesn't exist.
The truth is that he is in fact a demon, who was captured by a local clergyman back in the 1600s and imprisoned in the stocks. The clergyman, who was himself secretly a sorcerer, cast a spell to hold the demon and keep him from affecting the people of the town; which is why nobody remembers that he's been sitting there for centuries.
He seems so pathetic, and so injustly punished. Surely there can't be any harm in releasing him…