Obviously, the cecaelia could be the main antagonist. With its tentacles, it poses a direct threat to the girl. It might be using its strength and the reach of its tentacles to keep the girl from achieving her goals, whether that's escaping or finding something in its domain.
One possible plot could be that the girl is trapped in an underwater world where the cecaelia (a half - human, half - octopus creature) lives. She might be struggling to escape the tentacles which could be used by the cecaelia to either hold her in place or as a form of intimidation. Maybe she's there by accident, like she was on a boat that sank and she ended up in the cecaelia's lair.
I'm not entirely sure as it could vary greatly depending on the author's creativity. It might involve Sakura from a particular series in a difficult situation within Naraku's tentacles, perhaps in a battle or some sort of captivity scenario in the context of fan - created fiction.
I'm sorry, but I'm not aware of any specific fanfictions with this theme that are non - adult. However, you could try searching on fanfiction - specific websites and use their filtering options to find appropriate works.
Another theme might be that of discovery. Rain could be in the process of discovering the true nature of the dark gundam tentacles. This could lead to revelations about the Gundam universe itself, or about some hidden powers or secrets that are related to these tentacles. It might also be a journey of self - discovery for Rain as she faces this new and difficult situation.
You could try searching on popular fanfiction websites like Fanfiction.net or Archive of Our Own (AO3). Just use the exact title in the search bar and see if any results come up.
It could be an evil sea witch. In a fairy - tale - inspired fanfiction, an evil sea witch with the power to control tentacle - like sea creatures would be a great antagonist. She might see Ezra as a threat or simply want to use Ezra for her own dark purposes.
Maybe in the 'ezra struggles in tentacles fairy tale fanfiction', Ezra is a character who has been lured into an underwater world. In this world, there are tentacle - like creatures that are trying to keep Ezra there for some unknown reason. Ezra has to use their wits and any magical abilities they might have to escape from these tentacle - based imprisonments. It could be a journey of self - discovery as well as a fight for freedom.
I'm sorry, I haven't come across specific 'Rain Struggles in Dark Gundam Tentacles' fanfiction works. You can try searching on some well - known fanfiction websites like Archive of Our Own or FanFiction.net.
One common theme is the fight for freedom. The girl in the story is often trying to break free from her captors. Another theme could be the psychological impact of captivity. It shows how the girl copes with the trauma and fear.