It's hard to say for certain. The Harry Potter fanfiction community is vast and diverse. Some writers like to create alternative universes where characters have completely different relationships. But given the nature of Harry and Lucius in the original series - one being the hero and the other a Death Eater - making them brothers would require a great deal of imagination and explanation. The writer would need to explore how this new relationship would affect the plot, the other characters, and the overall themes of the story. It might also change the way we view the magical world's social and political structures as they are presented in the books.
Lucius' need in Harry Potter fanfiction could be power. He was always power - hungry in the original books. In fanfiction, this could be explored further. For example, he might try to find new dark magic artifacts or form new alliances to gain more power. He could also need revenge. If he feels that certain characters, like Harry Potter or the Weasley family, have humiliated him or his family, he would seek revenge in various creative ways that fanfiction writers can come up with. Maybe he would use his wealth and influence to undermine their reputations or set up elaborate traps for them.
Yes, there are likely fanfictions with such a concept. Fanfiction writers often come up with creative and out - of - the - box ideas. This particular one might explore an alternate universe where Harry Potter has a very different family origin. However, it would deviate greatly from the original canon of the Harry Potter series.
Harry would probably be extremely cautious. He has a strong sense of right and wrong, and Lucius has been on the wrong side in his eyes. Harry would be analyzing Lucius' every move, trying to understand if this is some sort of new Dark Arts plot or if there's something else going on. He would also be worried about the implications for his friends and the wizarding world in general.
Yes, it could be. Hogwarts is a very important place in the Harry Potter world, and Harry Potter is the main hero. So it makes sense that protecting Hogwarts by Harry is a popular theme.
Sure, in the realm of fanfiction, the sky's the limit when it comes to pairings. The concept of Harry married to Lucius could be part of a fanfic that aims to rewrite the entire 'Harry Potter' world from a different perspective. Maybe it's a story where the lines between good and evil are blurred, and their relationship is a key element in exploring new magical politics, family dynamics, or even a new form of magic that emerges from their union.
One common theme is redemption. Slytherins are often seen as the 'bad guys' in the original series, so protecting Harry gives them a chance at redemption. For example, they might be trying to make up for past wrongs or the actions of other Slytherins.
Maybe Lucius wants to use Harry for his own gain. Harry is a famous figure in the wizarding world, and Lucius could be thinking of leveraging Harry's status for something, like getting back into the good graces of the wizarding society after his fall from grace.
Sorry, I don't know of any specific fanfiction with that plot. You could try searching on popular fanfiction websites like Archive of Our Own or Fanfiction.net. Use keywords like 'Harry Potter Lucius brother' in the search bar to see if you can find what you're looking for.
One reason could be for the greater good of the wizarding world. If Lucius is healed, he might be able to turn away from the Dark side and provide useful information about Voldemort's remaining followers.