I am honor-bound to ask about the Sky WIP so, what going on with my boy there? BUT also! Murder Mystery on a Train?! Sounds delightful. :D If I can't pick two you can choose between them. ;)
You can absolutely pick two, thank you for the ask!
I think my only Sky one on the list was Sky on the surface, is that the one you mean? Since I made my list of autistic chain headcannons the idea of Sky going to the surface and being so completely overwhelmed and overstimulated lives absolutely rent free in my head. I haven't actually written anything for this one yet but I think about it a lot. The general idea of the fic will be that Sky goes to the surface, there's just WAY too much stuff for his brain to process and it's completely different to any routine he's used to, and Fi has to guide him to a safe space for a meltdown. And also Fi helps him figure out how to deal with so much stuff bc he's only used to Skyloft and that's small and always the same.
Murder mystery on a train is an idea that I LOVE but haven't done much for. Literally the only thing on the doc (besides my formatting stuff and such) is "i want an lu murder mystery on a train au" and that's it. I hope to get to it one day but I have other WIPs that are much more in progress so I haven't yet.