To survive, you should build alliances with the right characters. Also, stay away from obvious traps and don't trust everyone easily. Keep a low profile when necessary.
It would also affect the moral compass of the story. Hermione has always been a character associated with good and right. But with this new origin, she might struggle with her own identity and what it means to be 'good'. This internal conflict could be a major driving force in the fanfiction. It could lead to her making choices that are not so straightforward, and that would keep the readers on their toes.
Sure, in fanfiction there are no real limits. Luffy might survive eating another Devil Fruit if the author decides to create a new mechanism. For example, there could be a magical item or a rare fruit that cancels out the negative effects of consuming multiple Devil Fruits. Or perhaps his strong willpower and unique body constitution, which already allowed him to adapt to the rubber Devil Fruit, could also help him handle a second one.
This concept in fanfiction often allows for a new exploration of the magical world. The devil in this context could be a very different entity compared to traditional Christian or other religious concepts. It could be a more magical, other - worldly being. Hermione's heritage could also be linked to a different part of the wizarding world that was previously unknown, like a dark realm that has its own rules and magic.
"I Live in Utopia" was a short science fiction novel. It told the story of a person who lived in a society where patents were rampant and had to pay royalties for everything in his life. The protagonist lived in a perfect world, but he felt that everything was too fake and boring. I hope you like this fairy's recommendation. Muah ~😗
Hidekazu suffered the attacks of the Dark Palm and the Demon God Technique in the battle, but he still survived. However, the search results did not provide specific details about how he survived. Therefore, according to the information provided, I don't know how Shin survived.