Concerning all Final Fantasy games, they pull from multiple sources of inspiration so no doubt Final Fantasy XV Still pulls from "Shakespeare's Hamlet as well as Romeo and Juliet" and maybe a bit of "Baldr's Dream." I find it interesting that Luna has flower patterns on her dress and Ophelia from Hamlet is know for that kinda aesthetic. Also Stella, is probably her sister, and she is more like Juliet. Not to mention they also probably have a brother who is the hooded man. Though this is opinion and speculation based on various hints so it might be different.