Sure. Fanfiction often takes the existing characters and situations and twists them. For Harry and Dudley, it could start with a shared experience that makes Dudley realize Harry isn't so bad. Maybe they get caught up in a magical adventure together outside of the normal Hogwarts - related stuff. This common experience could break down the barriers between them and start a friendship.
Well, a common theme is the exploration of Dudley's character growth. In fanfiction, he may start to embrace the magic around Harry instead of fearing or hating it. This can lead to a friendship as he becomes more accepting. Another theme is the power of forgiveness. Harry forgiving Dudley for all the years of bullying, and Dudley being grateful for that forgiveness. And then there's the theme of learning from each other. Dudley teaching Harry about the non - magical world and Harry introducing Dudley to the wonders of magic.
Well, if Harry and Dudley became friends, it would drastically change the whole dynamic of the early Harry Potter story. For one, Harry might not have felt so alone at the Dursleys' place. Dudley could have protected Harry from Vernon's wrath. Also, they could have shared secrets about the wizarding world with Dudley being a Muggle. This new friendship might even have led to Dudley developing an understanding and acceptance of the magical world much earlier, and perhaps he could have been an ally to Harry in the fight against Voldemort, instead of a bully.
One possible plot twist could be that Dudley discovers he has some latent magical ability. This would completely change their dynamic as Dudley has always been the 'Muggle' bully. It could lead to him having to rely on Harry for guidance in the wizarding world, which in turn would force them to become friends as they navigate this new situation together.
It could develop after a major event changes Dudley's perspective. Say, Dudley witnesses the true extent of the danger Harry faces in the wizarding world. This could make him feel protective of Harry. He might start to defend Harry against their parents' unfair treatment. And Harry, seeing Dudley's change, would be more open to being friends. They could then start to communicate more, sharing their hopes and fears, and slowly but surely, a friendship would form.
Well, perhaps Dudley uses his street - smart knowledge. He might teach Harry some rough - and - tumble moves he's learned from his own scuffles in the neighborhood. For example, showing Harry how to dodge a punch quickly.
Harry might become more open and less guarded. Since he now has a brother in Dudley, he might feel more at home in the Muggle world. Dudley, on the other hand, could become less of a bully. The knowledge that he has a wizard for a brother could make him more humble and empathetic.
I'm not sure if there is a specific 'Dudley Gets Harry mpreg fanfiction'. Fanfiction covers a vast range of ideas and pairings, but this one seems rather unusual. It might exist in the extremely diverse world of fan-created works, but it's not a common or widely - known type of fanfiction. You could try searching on specialized fanfiction websites to find out for sure.
Maybe Dudley sees a different side of Harry through fanfiction. He might be curious about the magical world from Harry's perspective that he didn't fully understand before. Fanfiction often explores characters in new and interesting ways that could intrigue Dudley.
They could have adventures in the Muggle world. Maybe they would explore abandoned places in their neighborhood. Dudley, with his knowledge of the local area, and Harry, with his courage and magic (if he could use it secretly), could discover hidden treasures or solve mysteries. For instance, they might find an old diary that has some connection to the wizarding world but was lost in the Muggle world long ago.