There are so many possible interpretations of 'cari farver story'. It could be a family heirloom of a story passed down in a family where Cari Farver was an important figure. It might also be a new, emerging story in a particular community or among a group of friends. If you can give some more background information, like where you heard it or what genre it might be, it would be easier to explain.
I'm not sure who Aku specifically is. Aku could be a person with a great imagination who tells all kinds of stories, like adventure stories, fairy tales or even true - life stories.
It could be someone from the Naruto universe who doesn't like Naruto's newfound fascination with Aku. For example, Danzo might see Naruto's interest in Aku as a threat to the stability of the village and try to stop Naruto from further exploring Aku - related things. So, Danzo could be the main antagonist in this case.
The character of Aku could be developed in a 'pregnant Aku in Samurai Jack fanfiction' by exploring how he interacts with the world around him differently. He may become more reclusive as he doesn't want others to see his 'weak' state. Or he could become more aggressive in trying to protect his pregnancy, which would be a new aspect of his character. Also, his relationship with his own power might change. Maybe he has to find new ways to use his magic that don't harm the unborn, which would force him to grow and adapt in ways he hasn't before.
One idea could be a crossover where Aku accidentally opens a portal to the Naruto universe. Naruto, being the curious and brave ninja he is, decides to explore Aku's world. They could start off as enemies, but gradually come to understand each other's motives and end up teaming up against a greater evil that threatens both of their worlds.
I don't know the 'cari farver' real story. It could be a name known only in a small group or a specific area. Maybe it's a new name for a startup or a local hero.
One popular theme is probably about her music journey. Fans might write fanfic exploring how she creates her music, her inspiration, and the process behind it.