One common theme is power combination. Since it's a crossover, fans like to see how the powers from different series interact. For example, in a Bleach RE and Dragon Ball Z crossover, the reiatsu powers combined with ki blasts can create some really epic battles.
Another interesting one is 'Bleach RE: The Crossover with Fairy Tail'. This story brings together the magic of Fairy Tail and the spiritual aspects of Bleach RE. It shows how the characters from both series would interact in various situations, from fighting common enemies to just having normal conversations. It's a great read for fans of both.
One idea could be that Ichigo Kurosaki from Bleach somehow gets transported to the Victorian era world of Black Butler. He could be mistaken for a demon or some kind of otherworldly being. Sebastian, being the ever - curious demon, might be intrigued by Ichigo's powers and his strong sense of justice. Another idea is that Ciel Phantomhive has to deal with Hollows suddenly appearing in his world. He enlists the help of the Soul Reapers from Bleach to combat this new threat. They could form an uneasy alliance where the Soul Reapers are not used to the complex politics of the Black Butler world, and Ciel has to figure out how to work with these super - powered beings.
I really like 'The Shinigami and the Ninja'. It's a well - written fanfic where the author does a great job of integrating the different mythologies and power systems. You get to see Bleach characters like Rukia in the Naruto world, dealing with things like chakra and ninja villages. It adds a fresh twist to both universes.
One characteristic is the exploration of new settings. Since it's a crossover, Toshiro is often placed in different fictional worlds or situations not in the original Bleach story. For example, he might end up in a steampunk world or a world with magic systems different from Soul Society's.
One interesting idea could be that characters from Bleach are somehow transported to the Naruto world during the Chunin Exams. For example, Ichigo could end up participating in the exams. He might use his Soul Reaper powers in the forest of death, which would give him an edge against the ninja there. His Zanpakuto skills could be misinterpreted as some kind of advanced ninja tool or jutsu.
A good 'Bleach' crossover fanfiction often has well - integrated universes. For example, if it's a 'Bleach' and 'Dragon Ball' crossover, the power levels and the different types of energy in both worlds should be combined in a believable way. If the fanfic just throws the characters together without any thought to how their worlds' rules work, it won't be as good.
One great Hinata crossover with Bleach fanfiction is 'Hinata in the World of Bleach'. It shows Hinata from Naruto ending up in the Bleach universe. She brings her unique skills and gentle nature to the story. It's interesting to see how she interacts with the characters in Bleach like Ichigo and Rukia.
Well, 'Renji's Unusual Crossover' is a fanfiction that stands out. It combines Renji with a post - apocalyptic world. His sword skills are put to the test in a whole new way as he battles against mutated creatures. The author does a great job of showing Renji's growth in this harsh new environment. Then there's 'Renji Meets the Superheroes'. In this one, Renji crosses paths with a group of superheroes from a different fictional universe. The clash and cooperation between his abilities and theirs make for a very interesting story.
Power and growth. Both Inuyasha and Bleach have characters with different levels of power. In crossovers, often a character from one series has to adapt and grow in the other's world, facing new challenges that test their power.