One idea could be that Ichigo has to hide his vampire nature from his friends at first. He struggles with the new instincts and powers, like enhanced speed and strength. Maybe he has to resist the urge to drink blood from his loved ones.
Another plot could involve Ichigo being part of a secret vampire society. He discovers that there are different factions among vampires, some good and some bad. He then has to decide which side he wants to be on and fight for what he believes is right.
Well, a plot could involve Ichigo being turned into a vampire against his will. He then has to deal with the internal conflict of his human morals versus his new vampiric instincts. He might find that some of his friends are scared of him, while others are determined to help him find a way to reverse the transformation. And there could be a love interest who accepts him despite his new nature, adding a romantic sub - plot to the story.
One idea could be Ichigo getting trapped in a virtual reality game world where he has to fight his way out using his Soul Reaper powers. Another could be a crossover where Ichigo teams up with other game characters to defeat a powerful in - game boss.
One idea could be Ichigo crossing over into a different anime universe like the Naruto world. He could meet Naruto and they'd team up against a common enemy. Maybe a powerful new threat that combines the powers of Hollows and the Tailed Beasts.
One idea could be that the OC has a special power that only activates when in close proximity to Ichigo. For example, the OC can sense Hollows from a great distance, which helps Ichigo in his battles against them.
Well, a cool crossover fanfiction could be with the DC universe. Imagine Ichigo meeting Superman. They would surely have different views on justice. Superman is all about truth, justice, and the American way, while Ichigo is more about protecting his friends and the spirit world. Their meeting could lead to some intense debates and also team - ups against powerful villains.
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.
One idea could be a crossover where Ichigo and Naruto are transported to a strange new world together. They have to combine their skills, like Ichigo's Zanpakuto abilities and Naruto's ninjutsu, to find a way back home.
Another fanfiction could be a story where Sakura, for some reason, is transported to the world of Bleach. She enrolls in the Soul Reaper academy, where she meets Ichigo. They start off as rivals, constantly competing in combat training and academics. But as time passes, they realize they have a lot in common and end up becoming good friends and allies.
Perhaps there's a world where vampires and Soul Reapers co - exist, and Ichigo and Orihime get caught in the middle of a power struggle between the two groups. Orihime's powers might be the key to peace, and Ichigo is determined to protect her.
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.