Something Smells Fishy.

They'll kill him if he refuses to join their alliance. Only a member of their alliance gets to keep the castle or it will weaken their alliance. Of course, they will give it up if a stronger alliance asks for the fortress. It's the general protocol that is executed in situations like this.

The flaming serpentine demon maintained. "I'm just saying. There is something fishy about this entire thing. How did a single high-rank demon take down a fortress in such a short time? Look at the fortress, it looks like it was eroded by something and I can smell a wrongness in the air."

The fat disgusting worm fly snickered and said. "I can't smell anything in the air. The fortress probably looks like this because of some unique spell. You're just a coward."