Maybe a fanfiction where a Hollow dragon forms an unexpected alliance with a group of Quincy. The Quincy initially want to use the dragon's power for their own purposes, but as the story progresses, they realize that the dragon has its own motives and a complex personality. They then have to decide whether to continue the alliance or turn against the dragon.
A cool concept could be a fanfiction set in an alternate universe where dragons are the original form of Hollows. The Hollows we know in the original Bleach series are actually the result of some ancient curse or experiment that deformed the dragons into the grotesque Hollows. A young Hollow - dragon tries to discover its true origins and reverse the curse.
A fanfiction could revolve around a Hollow gamer who discovers a hidden 'game mode' within the Bleach universe. This mode could unlock special powers or quests that are related to the lore of the series. The gamer then has to complete these quests while also dealing with the regular threats in the world of Hollows and Soul Reapers.
A plot could involve Ichigo being trapped in the Hollow world and having to find a way back. Along the way, he meets other Hollows with different personalities and motives, some of whom he befriends while others are enemies. He discovers secrets about the origin of Hollows and how it relates to his own powers.
Well, you could have an OC Hollow who was once a human with a tragic past. After becoming a Hollow, they retain some of their human memories and emotions. This could lead to some interesting internal conflicts as they struggle between their Hollow instincts and their human side. Also, a story where an OC Hollow teams up with other Hollows to take on a powerful common enemy, like a rogue group of Soul Reapers who are experimenting on Hollows in cruel ways.
The interaction between Hollows and other characters in the 'Bleach' universe is also a great concept. Some fanfictions might focus on how Hollows interact with Soul Reapers in non - traditional ways, like forming alliances or having complex relationships that go beyond the typical predator - prey dynamic.
Another great one is 'Hollow Ichigo's Redemption'. This fanfic explores the idea of Hollow Ichigo finding a sense of purpose beyond just being Ichigo's other half. It shows a more complex side to the usually chaotic Hollow Ichigo.
One idea could be that the Soul Reapers from Bleach team up with the Z - Fighters from Dragon Ball Z to fight a common powerful enemy. For example, a new type of demon that has the ability to absorb spiritual energy like in Bleach and also has the strength and fighting skills similar to the villains in Dragon Ball Z.
First, you need to do some research on the Bleach universe, especially about Hollows and any dragon - like elements that might already exist in the series. Then, think about the main character. Is it going to be a new Hollow - dragon hybrid? Or a Shinigami dealing with this new threat? After that, create an outline of the plot, like the introduction, rising action, climax, and resolution.
A great 'bleach crossover fanfiction' idea is to cross it with One Piece. The Straw Hat crew could end up in the Soul Society. Luffy's carefree attitude would contrast with the more solemn Shinigami. Also, a Bleach and Fullmetal Alchemist crossover where the alchemic principles are applied in the Bleach universe would be really interesting.
Another idea is that Ichabod Crane from Sleepy Hollow somehow travels to the Naruto world. He could be amazed by the chakra and different ninja clans. He might try to learn some ninja techniques to protect himself in this new and dangerous world.
One idea could be a time - travel plot where a modern - day character gets transported to Sleepy Hollow during the events of the original story. They could then interact with the classic characters like Ichabod Crane and Brom Bones, and perhaps change the course of the story. Another plot could be a 'what - if' scenario. For example, what if Katrina Van Tassel had some hidden magical powers that she used to protect Sleepy Hollow from the Headless Horseman? And a third idea might be to create a story where the Horseman is actually a misunderstood hero, and there's a bigger conspiracy in Sleepy Hollow that he's trying to expose.