I'm not sure specifically as there could be many different versions of such a fanfic. But generally, it might involve Ciel's journey to heaven, perhaps his experiences, the people or entities he meets there, and how he copes with this new environment.
Ciel is surely the central figure. However, there could be other characters from the original source material that have also passed on and are in heaven. Additionally, there may be original characters created for the fanfic, such as a special angel who has a particular connection with Ciel. There might also be antagonists in the form of fallen angels or some sort of heavenly bureaucrats who oppose Ciel for some reason.
Maybe Cisl goes to heaven due to some unexpected circumstances, like sacrificing their own life to save others. Once in heaven, Cisl might be reunited with lost loved ones and have a grand tour of the celestial realms, seeing all the beautiful and magical things there.
Well, in such a fanfic, Naruto seeing Hinata in heaven could be a really emotional moment. It might start with Naruto being confused about where he is and then suddenly spotting Hinata. Their encounter could lead to a heart - to - heart conversation. Maybe they would talk about their past, their dreams, and how they felt about each other all along. It's a great concept for a fanfic as it gives an opportunity to expand on their relationship in a more spiritual and emotional setting.
Well, it might be that Naruto goes to heaven after sacrificing himself to save the entire shinobi world. Once in heaven, he meets the Sage of Six Paths who teaches him even deeper secrets about chakra and how to further the peace in the afterlife realm. He could also encounter all the past Hokages there and they have long discussions about how to better the ninja world even from heaven.
One possible plot could be that Naruto arrives in heaven and meets all the past Hokages. He has deep conversations with them about his life, his struggles, and how he changed the ninja world. Maybe he also gets to see his parents again and they have an emotional reunion, sharing all the things they missed out on while he was growing up.
Well, the 'elijah goes to heaven kid story' might start by introducing Elijah as a special person. It could then describe the events leading up to his going to heaven. Perhaps there were signs from God, and then suddenly he was lifted up to heaven. It could be a story to teach kids about faith and the power of God. For example, it might show that if you are faithful like Elijah, great things can happen to you.
Naruto might meet Itachi in heaven. Itachi could finally reveal all the secrets and the true intentions behind his actions to Naruto. And they could become true friends without any misunderstandings. Additionally, Naruto could also meet Neji, and they would talk about how the ninja world has changed since Neji's sacrifice.
Well, such a story might involve the kid's exploration of the heavenly realm, encountering angelic beings, and reflecting on their earthly life. It could also explore themes of redemption and hope.