Well, in such fanfictions, it could be that the author invents new prophecies or backstories. They might say that there was a mix - up at the time of Harry's birth, and that he was actually Regulus's son all along. Or perhaps there are some items or memories that only make sense if Harry is related to Regulus, like a locket that has a special connection to both of them.
The story would also shift in terms of Harry's place at Hogwarts. His sorting into Gryffindor might be more complex. Since he's related to the Black family, which has a history of being in Slytherin, there could be an internal struggle within Harry about his house loyalty. And his friends, like Ron and Hermione, might react differently to this new revelation about his parentage as they've always known him as a Potter.
Fanfiction about these three can take many forms. For example, there could be time - travel fics where Harry goes back in time and meets Regulus and Sirius when they were younger. This could lead to all sorts of interesting plot twists, like Harry trying to prevent Regulus from joining the Death Eaters in the first place. Or it could be a fic where Sirius survives and he and Harry explore the secrets of the Black family together, including things that Regulus left behind. There are also fics that focus on the emotional bonds between the characters, showing how the different personalities of Regulus, Sirius, and Harry interact and influence each other.
Luna Lovegood's child could be a great pairing. They could have an interesting dynamic, with Luna's child having a very different and whimsical view of magic, which would contrast and complement the son of Harry and Regulus. Another good character to pair with him could be Neville Longbottom's son or daughter. Given Neville's history of standing up to Voldemort, his offspring could bring a sense of courage and plant knowledge that could be useful in adventures with the son of Harry and Regulus. And of course, Ginny Weasley and Harry Potter's own children could be paired, as they would have a natural connection through their family ties.
Yes, there are likely some fanfictions out there with this concept. Fanfiction often takes creative liberties with established universes, and making Regulus Black Harry's father is an interesting and non - canonical twist. Writers might explore how this would change Harry's story, his relationships, and the whole wizarding world's dynamic.
One plot idea could be that the son discovers his father's past with Voldemort and tries to make amends for it in the wizarding world. He could use his unique position as the son of a former Death Eater and a hero's friend to bridge gaps between different factions. Another idea is that he has some special magical abilities inherited from both his father and the Potter side, which he has to learn to control while dealing with the expectations of others. And he might go on a quest to find hidden secrets left behind by his father related to the Horcruxes.
It's popular because it combines two very interesting characters. Harry is the main hero of the series, and Regulus is a mysterious figure with a complex backstory. Writers can explore what could have happened if they had interacted more directly.
One common theme is redemption. Regulus is often depicted as seeking redemption for his past mistakes, and Harry can be a catalyst for that. Another theme is family secrets. Since both are part of complex wizarding families, there are always secrets to uncover.
One common theme is redemption. Since Regulus was once part of the Death Eaters and then turned against Voldemort, many fanfictions focus on his journey to make up for his past mistakes. Another theme is family secrets. The Black family has a lot of hidden history, and fanfictions often explore how Regulus was affected by these secrets and how he dealt with them in relation to Harry Potter's story.
One interesting fanfiction could be 'The Lost Black'. In it, the daughter of Regulus Black plays a crucial role in uncovering some long - forgotten secrets in the wizarding world. She teams up with Harry Potter and they go on an adventure that spans from the hidden corners of Hogwarts to the dangerous Forbidden Forest.