So...I guess I was going to make a linear story, and I figure I needed some help converting it to a CYS format after some forethought. It's mostly just questions on how to expand my plot to make the shifts likable for readers, so grammar and style won't be shown much.
The initial story is broken into three chapters, and the "vanilla" plot would be centralized around a siren who is stuck on an island. Unlike the misconception of the modern day, this one is actually deformed to some extent so that her part-bird, part-man lineage continues to be a difficult obstacle to overcome throughout her life. The only way she can feed and shelter herself is by luring in animals and sailing ships with her singing. It's been years now, and loneliness is getting the better of her.
She's encouraged to swim after a shipwreck survivor swam all the way to the other shore, just at the horizon where the sun sets, but she fears she cannot escape given the fact the island is surrounded by sharp rocks, her family killed by a mass suicide in the ocean, and that her body wasn't strong enough for the task. From there, she can make a number of decisions, but I'd rather hear a suggestion from you guys to continue on this part with alternate paths.
In the vanilla, she does get to shore years later, and finds the entire continent is razed with a plague. The sailor she met dies in her arms, leaving her with an emptied village to take care of. She, apparently immune to the plague due to her biological incompatibility with the disease, will then rebuild a haven for others to live in.
The scene then transitions towards a village in the far north, filled with the Frost Men from Pathfinder. From the viewpoint of a hunter, the next story plays out to show the secluded lifestyle and struggles they have against humans from the south, when they are suddenly terrorized by a hag (in this universe, hags are women with partial immunity to the disease). The hunter is the victim of her seducing magic, and village remains vigilant for their children. From there, it could go a number of ways, but again...you guys.
In the vanilla for this one, the hunter gets exiled after decapping the hag and sparing the baby inside. He travels south, and shepherds a small herd of yak. He gets murdered by a scouting party of rather aggressive plague survivors, but not before taking them all with him by freezing them all to death.
The third chapter will transition to the siren from before, now a changed woman. She had, over the course of a series of surgeries, clipped off her webbed membranes and relocated her bones to accommodate for her now more rigorous lifestyle as a scavenger. She adopts the hag-spawn and takes the yak, and goes back.
From there...well, it could go a big, big number of ways. It's at this part where I'm at a loss for where to go next, so I want more ideas and stuff. If you guys would kindly do so.