A Demon of the Sea - Gravity Falls
Dipper is an aspiring author looking for work on the sea for something to write about. He is going around a port city asking around on different ships one night when he stumbles upon she ship of the Demon of the North Seas, Captain Bill Cipher. He is taken prisoner for a night, not knowing whether he would live or die. But Bill allows him to live if he becomes part of the crew, and he starts taking a liking to the brunette.
I said I was going to do a series of Billdip one-shots next but I lied (apparently). I got this idea and I couldn't stop myself! This is a thing that's happening now XD I'll still probably do the other thing on the side as well.