A third idea is that Naruto discovers a secret passage in the Blood Prison that leads to a hidden training ground. He uses this discovery to train in secret and also uncovers a conspiracy among the prison staff about using the inmates for some dark experiments. He then has to expose the conspiracy and free the inmates from this potential threat.
Another plot could involve Naruto having to deal with a hidden power within the Blood Prison that is starting to corrupt the inmates and guards alike. He has to find the source and stop it. For example, there could be an ancient curse that was placed on the prison long ago and is now awakening. Naruto, with his strong will, tries to resist the curse's influence while also finding a way to break it for everyone else.
One idea could be exploring a character's backstory who was wrongly imprisoned in the Blood Prison. For example, a shinobi who was framed by a powerful enemy and has to prove their innocence while dealing with the harsh conditions and dangerous inmates in the prison.
Well, a plot idea could involve Haren being framed and sent to the Blood Prison. Once there, he uncovers a conspiracy that reaches outside the prison walls. He then has to find a way to expose it while dealing with the prison's internal power struggles and dangerous inmates. This could involve using his wits and any latent ninja skills he might have.
One idea could be the main character having to protect the harem members within the dangerous Blood Prison setting. Maybe there are secrets about the prison that only the harem members know, and they rely on the main character to uncover them while fending off other threats.
In some fanfictions, Naruto might gain an unexpected power - up while in the Blood Prison. This new power allows him to not only escape but also take on the forces that put him there in the first place. It could be related to his Uzumaki heritage or a new form of sage mode.
Perhaps a fanfic where Naruto's blood has some special connection to an ancient and powerful demon. The demon is slowly being awakened due to some dark magic related to Naruto's blood. Naruto has to face not only the threat of the demon but also the distrust from some in the village who think his blood is a danger. He must prove that he can control this situation and keep the village safe.
In a 'dark blood Naruto fanfic', the dark blood could give the wielder the ability to see the darkest secrets of others. Naruto, with his new power, uncovers a conspiracy within the ninja world that is far more dangerous than anyone thought. He has to use this power, which is feared by many, to save the world while also dealing with those who want to stop him because of his 'dark' ability.
One interesting plot point could be Naruto's struggle to maintain his positive outlook in such a dark place. The Blood Prison is known for its harshness, and seeing how Naruto stays true to himself would be engaging. Another could be his interactions with the other inmates. He might form unexpected alliances or rivalries.
One interesting plot twist could be that Naruto discovers a hidden power within the Blood Prison that is related to an ancient clan. This power gives him an edge in battles and also helps him to uncover secrets about the prison's origin.
Maybe a fanfic where Naruto himself is imprisoned by an enemy village that has a false accusation against him. He then tries to break out not just for his own freedom but also to prevent a war that the false imprisonment might trigger. He could inspire other prisoners to join his cause through his unwavering spirit.
There are indeed alternatives. Some fanfics might explore the relationships between Naruto and other characters in the Blood Prison context. For example, they could depict how Naruto interacts with the guards or other prisoners in a way that promotes the values of the Naruto universe, such as perseverance, loyalty, and friendship. It's important to avoid the offensive ones and seek out the positive fan - created stories.