Well, one common theme could be secrecy. Since this type of relationship is often seen as taboo, the characters in the fanfiction may keep their feelings hidden from others. Another theme might be internal conflict. The siblings themselves would struggle with their inappropriate feelings, torn between their love and the knowledge that it's not socially acceptable.
I really like 'Darker Ties'. In this fanfiction, the idea of Harry and Hermione being siblings is explored in a very unique way. There are a lot of plot twists. For example, their family history is intertwined with some dark secrets of the wizarding world. It's a page - turner as you keep wondering how their relationship as siblings will evolve in the face of all these revelations.
There are various 'dark siblings fanfiction' out there. You might find ones where the siblings are in a cult - like situation, and they have to fight against the dark forces within the cult as well as deal with their own strained relationship. Some stories could also revolve around a sibling being haunted by the actions of the other in a supernatural setting, like a haunted house scenario where the past deeds of a sibling are coming back to haunt the present.
I don't really encourage the idea of 'dark love' between siblings as it goes against ethical norms. However, if you're looking for well - written fanfiction in general, websites like Archive of Our Own have a vast collection. You can search for tags like 'family relationships' in a non - inappropriate way and find some interesting stories that explore complex family dynamics in a more positive and healthy light.
Well, it's the novelty of the concept. We're so used to seeing them as friends in the original series, so making them siblings adds a whole new dynamic. It allows for different types of relationships to be explored, like a more protective or even a competitive sibling relationship.
First, think about the characters. Develop their personalities, especially the dark aspects. For example, one sibling could be overly possessive. Then, decide on the setting. A gloomy, isolated town can set the mood well. Next, create a conflict, like a family heirloom that both siblings want but it has a dark power.
In some fanfictions, their relationship develops through shared experiences. For example, they might fight together against a common enemy. This would make them rely on each other and understand each other's strengths and weaknesses better, thus deepening their sibling bond.
One interesting storyline could be them uncovering a long - hidden family secret. Maybe there was a third sibling they didn't know about, and they go on a journey to find this mystery person. Another could be them dealing with a threat to their family that only they, as siblings with their unique abilities, can face.
In some fanfictions, the siblings could be entirely new characters created by the author. They might have unique ninja abilities like one sibling could be a master of wind and water jutsus combined. Another could be a prodigy in genjutsu, stronger than Sasuke in that aspect. And the third might be a non - combatant sibling who is more into the political and diplomatic side of the ninja world, helping Naruto in a different way than fighting.
In some fanfictions, they might be reimagined as siblings. However, in the original 'Twilight' series, they are not siblings. Fanfiction often takes creative liberties to explore different relationships between characters.