Many 'little ichigo fanfiction' works have the theme of mystery. Given that Ichigo's father has secrets and the whole world of spirits is full of mysteries, when Ichigo is younger, he's starting to uncover these things. This can lead to exciting storylines where he's constantly learning new things about his family, his powers, and the hidden world around him. For example, he might start to suspect his father's true identity and embark on a little investigation of his own as a child, which makes for an engaging read.
One common theme is growth. Since Ichigo is depicted as little, his journey of becoming stronger and more aware of his powers is often explored. Another theme could be friendship, like how his relationships with his friends in Karakura Town develop at an earlier stage.
One common theme is the exploration of different worlds. Since Ichigo comes from a very different world compared to My Little Pony's Equestria, stories often focus on how he adapts and what he discovers in this new magical place.
One common theme is the battle between good and evil within Ichigo. His normal self represents the good, while Dark Ichigo represents the more primal and sometimes malevolent side. Another theme is self - discovery. As Ichigo grapples with Dark Ichigo, he often discovers new aspects of his own power and personality.
A common theme is the exploration of their dual natures. Since Ichigo has his own powers and the female hollow ichigo has her unique hollow characteristics, fanfictions often play with how these two different yet connected aspects interact.
Friendship is also a big theme. In many Ichigo harem fanfictions, the relationships start as friendships. For example, Ichigo could be friends with a group of people, and as the story progresses, some of those friendships turn into romantic feelings. Another theme could be the power dynamics. Given Ichigo's abilities in the original story, how he relates to those in his harem who may or may not have similar powers can create interesting plotlines. The harem members might look up to him, or they could be equals in terms of power, and this affects how their relationships develop.
Another theme is friendship. Given that both characters are known for their strong bonds with their friends in their original series, fanfictions like to explore how they would form a friendship with each other. They might start off as rivals and then grow to respect and trust one another over time.
One common theme is power combination. Since both Naruto and Ichigo have distinct and powerful abilities, many fanfictions explore how these powers can be combined. For example, Ichigo's swordsmanship combined with Naruto's ninjutsu.
One common theme is power - up. Since Ichigo is becoming transcendent, it often involves him gaining new and extraordinary powers that set him apart from his normal self in the original series. For example, he might have the ability to manipulate time or space.
One common theme is the development of relationships. It shows how Ichigo forms bonds with the different characters in the harem.
Love and romance can also be a theme. In some fanfictions, Ichigo and the fem character develop romantic feelings for each other. Also, the theme of power - sharing or teamwork is often seen. They combine their unique abilities to face powerful enemies. For instance, if the fem character has some magical powers, she and Ichigo with his Soul Reaper powers work together. This is often used to create exciting battle scenes and story arcs.