Harry's personality would be a far cry from what we know. He'd be more likely to be power - hungry and less concerned with the well - being of others. Bellatrix's influence would make him see the wizarding world in terms of pure - blood superiority and the use of force. He may not have the same sense of humor or the ability to make friends easily, as his values would be so different.
In this fanfiction, Harry's personality would be deeply influenced by Bellatrix. He could be cold - hearted and sadistic. Since Bellatrix was a fanatical follower of Voldemort, Harry might also have a strong sense of loyalty to the dark side. He would not be the selfless hero we know. Instead, he would be more focused on his own gain and the domination of the wizarding world. His moral compass would be completely skewed, and he might not have any qualms about using dark magic to achieve his goals.
In a 'bellatrix is harry's mother' fanfiction, the plot could be quite wild. For example, Bellatrix could have been forced to give up Harry at birth due to her position as a Death Eater. Years later, Harry discovers the truth through some magical means. This could lead to a series of events where Harry tries to understand his mother's true nature. Bellatrix might also have a change of heart and try to protect Harry from Voldemort, which would create a lot of tension and drama as she has to balance her two loyalties. It would be a complete departure from the normal 'Harry Potter' narrative and would offer a very different perspective on the characters.
One big challenge would be trust. Bellatrix has been a loyal Death Eater and has tried to kill Harry many times. Even in pet form, Harry would have a hard time believing she wouldn't turn on him if she regained her normal form. Another challenge would be how others in the wizarding world would react. The Order of the Phoenix might not trust Harry's decision to keep her around, even as a pet.
If Bellatrix was Harry's mother in this fanfiction, the whole plot would be a mess. Harry would be born into a family of pure - blood maniacs. His magical education would likely be focused on the dark arts rather than the normal curriculum at Hogwarts. His relationships would be warped. He may not have the same friends like Hermione and Ron. And his relationship with Voldemort would be extremely complex, as Bellatrix was one of Voldemort's most loyal followers. It would be a story full of moral and ethical dilemmas for Harry.
If Bellatrix was Harry's mother, his life would be a complete departure from what we know. He'd grow up in a world full of fear and secrecy. Bellatrix's reputation as a Death Eater would mean that Harry would constantly be in danger, not just from Voldemort's side but also from those who oppose the Dark Arts. His education would be different too. Instead of Hogwarts' traditional curriculum, he might be taught more about the dark secrets of the wizarding world. His relationships would also be affected. He might not have the same friendships as he does in the original story, as his mother's actions and beliefs would isolate him from many in the wizarding community.
It would be very strange and interesting. It might involve a complete rewrite of the backstories. Maybe there would be a hidden family connection that was somehow overlooked in the original story. Harry's character might have some of Bellatrix's traits, like her fierceness or her loyalty (albeit to different sides in the original story).
Harry would likely be more conflicted. With Bellatrix's influence, he might have a darker edge to his personality. He could be more aggressive in his approach to problems. Sirius, on the other hand, would try to keep him on the right path, so there would be an internal struggle. He might not be as quick to trust as the original Harry, but more cautious and calculating.
Voldemort is often paired with Bellatrix in fanfiction. Their relationship in the original series was one of master and servant, but in fanfiction, it can be explored in more complex and romantic ways. Another character often paired with her is Narcissa. Their sisterly bond can be a central focus, or it can be twisted into something more sinister or complex in fan - created stories. Also, sometimes Sirius Black is paired with her in alternate universe stories, given their family connection and the contrast in their loyalties.
He would probably be more conflicted. On one hand, he would have the potential for great good, like the original Harry. But on the other hand, he would have the shadow of Bellatrix's dark deeds hanging over him. This internal conflict could make him more withdrawn at times. He might also have a fascination with the dark arts, not in an evil way, but more out of a need to understand his mother's world. This would set him apart from the Harry we know, who was always more firmly on the side of light magic.
Fanfiction allows for all kinds of wild ideas, and the idea of Bellatrix being Harry's biological mother is one of them. It's a very strange concept when you think about the established facts in the 'Harry Potter' universe. Bellatrix was a devoted follower of Voldemort and was involved in many dark deeds. Lily, on the other hand, was a loving mother who sacrificed herself for Harry. But in fanfiction, an author could rewrite the backstory in such a way that Bellatrix had some sort of connection to Harry's birth. Maybe through some dark magic or a convoluted plot twist, but it goes against the grain of the original story.
It would be extremely dark. Harry would likely grow up in a very different environment, surrounded by Death Eaters and their ideology. His relationship with the Order of the Phoenix would be completely changed. Maybe he would be more conflicted about his loyalties, not as straightforward as in the original story.