One of the horror stories from Mali's history could be related to the various invasions it faced. For example, the Moroccan invasion in the 16th century. The Moroccans had superior military technology at that time, which brought great destruction to Mali. Many cities were sacked, and the local people suffered a lot. Their way of life was disrupted, and there was a significant loss of life and cultural heritage as well.
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.
During colonial times, Mali was under French rule. The French imposed their own systems which sometimes clashed with the traditional Malian ways. There were forced labor practices, and the Malian people had little say in their own governance. Their resources were exploited, and this led to a lot of resentment among the people. It was a difficult and often oppressive period in Mali's history.
The scariest element is often the sense of the unknown. In Mali horror stories, there are often mysterious forces at work that people can't explain. For example, the unexplained noises and movements in haunted places.
One main theme is leadership. For example, in stories about Sundiata, his leadership skills in uniting the Mali people are a central focus. Another theme is cultural heritage. Mali has a rich cultural history, and in historical fiction, elements like music, oral traditions, and family values are often explored. Also, the theme of trade is common as Mali was an important trading center in Africa.