I segreti di Nicholas Flamel l'immortale: I gemelli

The world-building felt seamless and immersive, but I'm curious whether the myth influences were planned from the start or evolved during writing.

The protagonist's journey felt very personal and inspiring, but I wonder if others found certain character arcs more compelling or predictable.

The magic felt both mystical and logical, which is rare. I'm interested in whether the author crafted this system first or let it develop organically through the story.