A/n: In this AU there will be bloody scene and Bill is a lot violent (or at least, I'll try to write scene with this things)

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Bill, the Captain of the legendary "Weirdmageddon", whose name was known in all the Seven Seas.

The Captain wasn't an ordinary pirate, during his travels he has found many magical creatures. Once he even found a demon and managed to cheat and kill him. The demon was amazed by his subtle, cunning and cruel mind, so before he die, he gave to him his powers and his millennial knowledge, so Bill became a demon but his body remained human. He continued to travel, becoming more and more powerful both as a demon and as a pirate, but because of his mortal body, the stronger the opponents he faced, the more severe the injuries he suffered. One day he remembered the legend of the tears of the sirens. Rumors said they were able to heal all the ills or wounds even if you were dying, so he decided to search one of them.

Unlike all the pirates who had tried to capture these magical creatures before by attacking them from the ground and using people as lure, Bill knew a place to easily find a siren and caught it: Siren Falls. According to the legend, on that island there was a salt water pond with a passage that leads to the open sea. If a siren came into that pond and sang a song in a night with full moon, it could gain the power to turn its tail into a pair of legs singing the same song sung in the pond.

When they berthed the ship, Bill told the crew to prepare a big tub full of sea water and leave it in front of his cabin door, then he got on a lifeboat and he rowed toward Siren Falls. Once he arrived on the ground, he entered into the woods. After an hour, he heard a melodious voice and followed it until he saw a pond hided by trees and bushes. He hid behind one of them and listened to the siren singing under the silver moonlight.

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A/n: this is the song Dipper is singing:

https://youtu.be/7DM1LC2EWbg

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Bill was enchanted by the siren's voice, despite it wasn't one of those songs for hypnotize the sailors and bring them to their deaths so he waited for the end of it. The siren gave off a blinding light and when it faded it found itself with legs. Bill heard the siren laugh and saw the glow again indicating that it was changing shape. At that moment Bill came out of his hiding place and summoned a magic rope wrapped itself around the siren's body as he put the creature to sleep with another spell before it tried to escape.

Once Bill pulled it out of the water and lifted it up bridal style, the Captain finally managed to see well the siren: it had short brown hair and its fins and tail were dyed with the most marvelous blue he's ever seen. Some scales were luminescent and its skin shone under the moon's rays. It had gills on the neck and under the ribs, a webbing between the fingers, black nails and an old necklace around his neck with the shape of a stylized pine tree. But the thing that surprised him the most was that the siren was a boy. He knew there were males sirens but they weren't allowed to go on the surface or go to hunt because they were a lot less then the females but the males were more lethal and their voice were more beautiful.

Returning to the ship, his crew looked in amazement at the creature in the Captain's arms, sleeping peacefully. He put it in the tub and then he dragged it into his cabin.

Using his magic again, he tied its arms behind his back with his tail to keep him from leaping out of the tub and put a gag on his mouth, then he closed his cabin door to make sure no one could see him doing magic, he summoned his blue flames and snapped his fingers to awaken the siren.

It opened its eyes lazily but immediately noticed the heat of the flames that enveloped the Captain's hand dangerously close to his face and tried to stay away from it as much as possible.

B: Listen, siren , I need you to cry for me and give me your tears. If you obey me without making a fuss, I'll cut your throat and you'll have a quick death, otherwise I'll torture you until you'll cry blood and I will not stop doing it even if you'll ask for mercy. Now I'll take off the gag and you won't dare try to hypnotize me with your voice or bite me I swear that the deal it's already broken and I'll tortures you without giving you choice. Nod if you've understood.

The siren nodded quickly and it relaxed when the flames went out and Bill took off the gag.

?: P-please, spare me... I don't want to die...

B: Then I think I'll take them by forc-

?: WAIT WAIT WAIT! I-i didn't say I won't to give you my tears! I-it's just that... I don't want to die... not now that I can finally have legs!... C-can we change deal?

Bill crossed his arms with a threatening look.

B: I'm listening.

?: C-can I join your crew...?

Bill looked at him surprised.

B: What?! Why this?

?: I-i've always dreamed of leaving for adventure, visiting distant seas, seeing the mainland and then leaving for places far far away. So... please, could you spare me and make me part of your crew? I'll give you all the tears you want as soon as you need them and you will give me the opportunity to study the humans, learn to be like you... (or, like them, I've never seen a human use magic so I think you aren't completely human) and you'll show to me the seas too far away to reach them all alone and the mainland when we'll reach a port or we'll have to look for a treasure. I want to see what a forest is like and what kind of animals you have up here. I want to hear new songs and mostly read books on many things without them becoming wet. So, please, spare me. I'll do whatever you want, I'll become a good member of your crew, I'll give you my tears and sing for you if you'll need it.

Bill looked the siren begging him remaining silent, then he sighed and freed him from the ropes by snapping his fingers. The siren stretched and the Captain's flames revived around his hand but this time the siren didn't feel any warmth coming from that and it looked curiously at the blue cerulean flames.

B: Don't worry, these flames don't burn, it's demonic magic. Once you'll shake my hand, our deal will be sealed. I will be your Captain and you will be my personal siren... 

D: D-dipper ...

B: What?

D: M-my name... is Dipper...

The siren blushed when the Captain started to laugh, then they shook their hands.

B: Welcome on the Weirdmageddon... Pinetree.

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1167 words

12/02/18