One main theme is the clash of cultures. Ichigo comes from a world of Soul Reapers and Hollows, while Naruto is in a world of ninjas. Their different values and ways of life often collide in these fanfics.
One idea could be that Ichigo and Naruto are brought together by some sort of interdimensional rift. They initially don't understand each other's powers but soon realize they share a common goal of protecting their friends and worlds. They could team up to fight a powerful enemy that threatens both their universes.
One popular ichigo crossover naruto fanfic is 'Soul Reaper in the Hidden Leaf'. It has an interesting plot where Ichigo ends up in the Naruto world and has to adapt to their ninja ways while still having his own Soul Reaper powers. It's really cool to see how he interacts with Naruto and the other characters.
Luffy from One Piece is also a common pairing. Luffy's carefree and adventurous nature combined with Ichigo's more serious and duty - bound personality would lead to some really fun and unpredictable interactions. They could be on a quest in a crossover world, with Luffy's devil fruit powers and Ichigo's Soul Reaper abilities working together in strange and amazing ways.
One common theme is power comparison. Fans like to see how Ichigo's spiritual powers stack up against Naruto's chakra - based powers. Another theme is friendship. They often write about Ichigo and Naruto becoming fast friends and learning from each other.
A more serious fanfic could be set in a post - apocalyptic world that was destroyed by a combined force of villains from both Naruto and Bleach universes. Naruto and Ichigo are the last hopes. They meet and initially clash due to their different ways of fighting and beliefs. But they gradually learn from each other and combine their powers in a unique way to take on the remaining villains and try to restore their worlds.
One common theme is power combination. Since Ichigo and Rukia have different powers, fics often explore how these powers can work together. For example, in many fics, they combine their spiritual energy to defeat a stronger foe.
Another concept might be Ichigo crossing over with superheroes from Western comics. Picture Ichigo fighting alongside Superman or Batman. His unique reiatsu - based powers would be a great contrast to the superhuman abilities of the superheroes, and they could learn from each other's fighting styles.
The plot could involve a dark force that is draining the energy from both the Bleach world and the Naruto world. Ichigo and Naruto are chosen as representatives of their respective worlds to find the source of this threat. Along the way, they encounter characters from both series. They might have some clashes at first due to their different personalities and ways of doing things. For example, Ichigo is more brooding and Naruto is more upbeat. But as they face challenges together, they learn to trust and rely on each other.
One interesting character to crossover with Ichigo is Light Yagami from Death Note. The clash between Ichigo, who is a protector, and Light, who is a morally ambiguous character with the power to kill, would be very engaging. Saitama from One - Punch Man could also be a great choice. Saitama's overpowered nature and Ichigo's journey to become stronger would make for an interesting story. And what about Alucard from Hellsing? His vampire powers and Ichigo's powers related to the afterlife would create a really dark and exciting crossover.