Well, in some fanfictions, Harry might use his advanced magic skills he learned from Dumbledore's old books. Maybe he discovers a long - forgotten spell that can reverse the dark magic effects on Lucius.
It could be that Harry has some kind of special connection with the Malfoy family's magic due to some unforeseen circumstances. For example, a magical bond formed during a previous encounter that allows him to access Lucius's magic core and heal it. He first has to figure out this connection, though, and then use it to his advantage to heal Lucius. He might have to fight off some of the dark influences within Lucius's magic at the same time.
In certain fanfiction scenarios, Harry might use his own pure heart and strong willpower. His positive energy could be a counter to the dark magic that has ailed Lucius. Harry, being the Boy Who Lived, has a unique kind of magic within him that could potentially be used to heal Lucius. He may start by purifying Lucius's mind, getting rid of the dark thoughts and then gradually heal his physical and magical ailments.
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.
Many 'Harry Potter Lucius Malfoy Mpreg Fanfiction' stories also explore his relationships in a new light. His relationship with his family, especially Narcissa, could be strained or strengthened. And his relationship with other Death Eaters or Hogwarts faculty might change as they react to his unexpected condition.
In some fanfictions, Lucius Malfoy might save Harry Potter out of a change of heart. Maybe he realizes the greater evil that Voldemort represents and decides that Harry is the key to stopping it. So he could use his position within the Death Eaters to provide crucial information to Harry or his allies.
He becomes more conflicted. Growing up as Lucius Malfoy's son, he is exposed to different values. So, instead of the Gryffindor - like straightforwardness, he may have a more calculating side.
Some fanfictions explore a more complex relationship. Maybe Lucius has a secret prophecy about Harry that makes him act in strange ways towards him. He might be torn between his loyalty to Voldemort and this new - found interest in Harry, which causes a lot of internal conflict and very different interactions with Harry compared to the original books.
There are some fanfictions where Lucius Malfoy becomes a mate to another character through a shared goal. For instance, in a story where the wizarding world is under a new threat, Lucius and another character might find that they need to combine their resources. Lucius, with his wealth and knowledge of the wizarding elite, teams up with someone who has different skills. They start off as reluctant partners but end up as true mates in the fight.
In a Harry Potter fanfiction, Lucius Malfoy could be forced into a situation where he has to work with someone he initially despises, but over time they develop a mutual respect and become mates. For example, he might be paired with a Muggle - born wizard during a special mission. At first, he is full of prejudice, but as they face challenges together, he begins to change his views and they form a strong friendship.
Yes, there are likely some fanfictions out there with such a plot. Fanfiction writers often explore alternative storylines, and this could be one of them. However, it's important to note that these are not part of the official 'Harry Potter' canon.
Fanfiction is a form of creative expression. While a 'Harry Potter and Lucius Malfoy' fanfiction might seem strange at first, if the writer is able to create a believable story arc that doesn't violate the core values of the Harry Potter universe, it could be considered okay. For example, if the story is about them having to work together in a difficult situation and learning to understand each other, rather than something inappropriate.
Sure, there probably is. Fanfiction allows for all kinds of wild ideas. Writers might be interested in exploring a relationship between Harry and Lucius to add a new layer of complexity to the story. They could be looking at how the two characters from opposing sides could interact in a different way than what's shown in the original books. But it's important to note that this goes against the normal portrayal of their enmity in the official series.