One idea could be to combine the magic systems. In Naruto, there's chakra, and in The Poppy War, there's shamanism. Imagine a character who can use both, creating unique combat styles. For example, they could use chakra - enhanced shamanic spells.
First, study the characteristics of both universes. In Naruto, characters often have strong bonds with their comrades. In The Poppy War, characters are shaped by their harsh upbringings. Combine these elements. For example, a character could be a former shinobi who lost their comrades and now in The Poppy War world, is cynical but still holds onto some of the Naruto values deep down.
Since it started as fanfiction, it might have initially been classified in the same genre as the work it was fanning. But as it became its own story, it could have blurred genre boundaries. For example, if it was a fanfic of a fantasy work, it might have added elements from historical fiction or military fiction as it developed, making its genre classification more complex.
One of the main themes is war and its brutalities. The novel shows the harsh realities of war, like destruction and loss. Another theme is power, both political and magical. Characters constantly strive for power, which drives much of the plot. And there's also the theme of identity, as the protagonist struggles to find her place in a world full of chaos and conflict.
Rin is definitely one of the most memorable. She is the protagonist and her journey from a war orphan to a powerful figure is quite engaging. Another is Altan, with his complex personality and his role in Rin's life. He has a great influence on her growth and the events of the story.
Well, starting as fanfiction might have given it an initial base of creativity. It could have borrowed some common tropes from the original work it was fanning. Then, as it evolved into its own thing, it had to break away from those fanfic roots. It might have had to re - define its characters and plot to be more unique and not rely on the pre - existing work's popularity. This process of transformation could have been both challenging and inspiring for the author.
Well, one key feature is its rich world - building. It creates a vivid and complex world full of different cultures and magic systems. Another is its strong characters who face moral dilemmas and grow throughout the story.