A cool plot could be Ichigo's hollow form getting separated from him and having its own adventures. It could encounter other Hollows and form unexpected alliances while Ichigo tries to find a way to reunite with it. This would show a different perspective of the Hollow side.
Perhaps in the fanfiction, Ichigo's hollow form could be used as a weapon by an enemy. They manage to take control of it and turn it against Ichigo and his allies. Ichigo then has to find a way to break free from the enemy's control and regain his hollow form as part of himself.
One idea could be exploring how Ichigo's hollow form affects his relationships with his friends. Maybe his hollow side makes him more aggressive towards them at first, but they gradually learn to accept and help him control it.
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.
One plot idea could be that Hollow Ichigo and Rukia are forced to team up against a new, powerful enemy that threatens both the Soul Society and the world of the Hollows. They start off distrusting each other but gradually learn to work together and understand each other's motives better.
One idea could be exploring the inner turmoil of Ichigo as a Hollow in a new and unique way. Maybe his Hollow side starts to have different desires that conflict with his normal self.
Well, a common plot could be Hollow Ichigo time traveling to key battles in the Bleach universe. For instance, he could go back to the fight between Ichigo and Aizen. He might interfere in the battle in unexpected ways, either helping Ichigo more than he should or causing chaos. Or he could time travel to when the Hollows first emerged and try to change the nature of Hollows from the very beginning. This could have a huge impact on the entire Bleach world and its power balance.
Maybe fem Ichigo has a different set of powers compared to Ichigo. In the fanfiction, they could train together to combine their powers in a unique way. For example, her powers might be more focused on defense while Ichigo's are on offense, and they learn to complement each other. This could lead to some interesting character development as they overcome their differences and work towards a common goal.
In some ichigo x hollow ichigo fanfiction, the exploration of their shared identity is really fascinating. They are two parts of the same whole, and fanfictions might delve into how they come to terms with that. Maybe they learn to co - exist in a new way that neither of them expected, leading to new character development for Ichigo as a whole.
Perhaps a plot twist where Dark Rukia discovers that Hollow Ichigo has a connection to her past that she was unaware of. Maybe he holds the key to unlocking a part of her memory that was sealed away, which changes their dynamic completely as they try to figure out what it all means.
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.
One idea could be that the Hollow Lemon is a unique type of Hollow with special powers. Ichigo encounters it during a routine patrol in Karakura Town. At first, he's cautious as he doesn't know what to expect from this strange Hollow. But as the story progresses, they find that they have an unexpected connection, perhaps related to Ichigo's inner Hollow. Maybe the Hollow Lemon has some information about Ichigo's past or his latent powers that he hasn't fully explored yet.
One idea could be Ichigo struggling to control his new vampire instincts while still trying to protect his friends. He might have to hide his vampiric nature from his family, which adds a layer of secrecy and tension.