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.
I'm not sure specifically which 'antara full story' you are referring to. There could be many things named Antara. It could be a name of a person, a place, a book, or a movie. Without more context, it's difficult to tell the full story.
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.
As I don't know the 'Antara Indian Series' well, I can't say for sure what the main characters are. But if it's named after 'Antara', she is likely to be one of the main characters. There might also be characters related to her family, like her parents, siblings, or perhaps a love interest.
As a fan of web novels, I don't have any knowledge about the plot and character settings of Star Travels. Therefore, he had no choice. It is recommended to read the original work or check the relevant background information to obtain more accurate information.
I'm not sure who specifically wrote the lyrics for a song titled 'lirik never ending story'. It could be written by the songwriter associated with a particular musical version of 'The Never Ending Story'.
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.