A few content warnings I can think of for now (?):
Pairing: Feitan
It's a self-insert romance (this is important; hopefully it won't put readers off, but honestly, it doesn't matter if you're not bothered by it), but essentially it's a Hunter x Hunter transmigration fanfic (though what I write will probably be pretty boring).
Just me rambling, not much logic. I might borrow settings from other works (?). I'll make it up as I go.
The story leans toward following the Hunter x Hunter plot, with original characters and storylines. There will be out-of-character portrayals, butterfly effects (minor plot changes), and so on.
There may be pairings such as Gon x Killua, Hisoka x Illumi, and Killua x Feitan, as well as romantic descriptions of original characters' feelings for Hunter x Hunter characters. BG/GB/BL/GL content may all appear.
A more proper synopsis:
The story of how I, a real-world Feitan fangirl, successfully transmigrated into Hunter x Hunter and tried to fulfill my wish.
Theme: Fulfilling your own wishes