Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.
I'm not entirely sure as there could be various stories within a Kenpachi light novel. It might be about the adventures, battles, or the character development of Kenpachi, a character who is likely to be strong and perhaps a bit of a maverick. Maybe it involves his relationships with other characters in the fictional world it's set in.
Sure. Given the popularity of both Naruto and Kenpachi, it's not far - fetched to think that a fan would create a story where Naruto is a Kenpachi fan. This could lead to all sorts of interesting plot points. For example, Naruto could seek out Kenpachi to train with him, or perhaps he just idolizes Kenpachi from afar and tries to emulate his strength and bravado in his own battles within the Naruto universe.
The appeal lies in seeing a different side of Kenpachi. His tough exterior in the original work makes the more tender or passionate sides shown in lemon fanfiction a contrast. It's like getting a peek into what he could be like in a more personal, non - battle - related context.