She might feel guilty. Since they are siblings, she could be aware of Naruto's neglect and try to make it up to him in small ways, like sharing her food or secretly leaving him little gifts.
Sure. There could be fanfics with this concept. Naruto is known for his own powerful abilities like the Rasengan and Sage Mode. But in the world of fanfiction, writers can bend the rules. Maybe in a story, Naruto gets the Susanoo as a result of a powerful curse or a gift from an ancient being. It would be really cool to see how he would use it in combination with his existing skills.
I'm not sure if there is such a specific fanfic. Fanfic writers come up with all kinds of creative ideas, but this one seems rather unusual. It's possible that in some very niche or less - known corners of the fanfic world, it might exist, but I haven't come across it personally.
I'm not sure if there is such a specific fanfic. Fanfics cover a wide range of themes, but abuse within family in a Naruto fanfic might be a rather dark and not - so - common take. It could exist in some corners of the vast fanfic community, but it would also be quite controversial as Naruto is generally depicted in positive relationships in the original series.
Naruto would use his ninja skills. He might start with a diversion, like creating some clones to distract the assassin while he gets his sister to a safer place.
Another theme might be mystery. The sister's existence could be tied to some hidden secrets in the story's universe. It could be about uncovering her past, her connection to certain events or characters, and how she affects Ciel's own journey which is often filled with mystery already.
One possible plot could be that Naruto's little sister is also a ninja in training. She might struggle with the same kind of ostracism Naruto faced because of the Nine - Tails inside him. However, she could also be a source of great support for Naruto, helping him through his toughest times and together they could train to become stronger. Maybe she has a unique ninja ability that even Naruto is in awe of.
Well, perhaps the story could be about Naruto finding out he has a sister who was hidden away for her own safety. Maybe she has some unique powers that the villains are after, and Naruto has to protect her while also learning about his family's past.
In the 'naruto has no will to live fanfic', it might explore Naruto's extreme state of mind. Maybe he has faced so many traumas and difficulties that he loses the will to live. For example, he could have witnessed the death of too many loved ones, like Jiraiya, and felt overwhelmed by the responsibilities on his shoulders.