That same night, Mildew had work to do. He couldn't convince these mindless Vikings to deny the belief that dragons were evil creatures, so he's going to force them to give them up. They may hate him now, but they'll thank him once they see how peaceful the island will be once the creatures have left the island.
He got out a piece of paper, a stick with charcoal and a stool, and he proceeded to write his letter.
He wrote and wrote and wrote, silently speaking under his breath as he did.
It was done:
Interested in Berk's wide array of dragons?
Meet me at the southern shore of Berk to create a deal at 22:00 tomorrow.
Don't be late
A friend
"Ah, this'll do it."
The crotchety old man took the note, furled it, and tied it with a string. He turned and walked to the corner of the room where he kept his very own pet: a messenger owl. No one on the island knew he had one.
He walked over to the bird, "C'mere Hector, I've got a job for you." The owl flew off its stand and landed on the old man's forearm. He tied the note to Hector's leg snug.
He walked out the front door, passed the giant rusting statue of Thor that must be removed, and stood on the edge of his railings. "Now make sure this gets directly to Alvin," he whispered. The owl leaped from his arm and flew off into the night sky.
All there was left to do now was wait for a reply.