Night falls, the demons arrive... and the gates are open and there's tea and biscuits in the bailey. -- Gallifreya
The Hordes of Darkness were on guard as they crept into the castle. They expected all kinds of resistance. Hails of arrows. Rains of fire. Boiling oil or at least scalding-hot porridge raining down on them from the murder holes.
There should have been armed knights. There should have been traps.
The demons were still expecting some. They even regarded the set tables in the vacant courtyard with suspicion. There was tea. Cake. Biscuits. Cucumber sandwiches. Salads and all kinds of snack-worthy fare. There were even rainbow macaroons.
The poison-sniffers detected nothing more hazardous than sugar. The rogues failed to spot any traps.
Finally, the leader snapped. "What the hell even is this?"
"It's called Parley," said a distant voice from the overlooking arrow-slits. "That means we all sit down to a nice meal and talk about our grievances. We leave our weapons behind and discuss compromises."
"Er," said the Dread Lord of Darkness. "You do understand we want to take over the world and make you our slaves... right?"
"Yes, of course. But the real question is why?"
The Dread Lord of Darkness faltered. "Uhm," he said. And, "Er..."
Inside the keep, Wander elbowed the current monarch in a friendly way. "See your majesty? Kindness always works."
 Historical fact - one castle in Scotland ran out of boiling oil to pour on an invading army, and the women in the keep substituted hot porridge. They won, and the porridge cauldron is still on the local coat of arms.