Well, perhaps Harry Potter could get a cybernetic arm after an encounter with a dark wizard's spell that damages his original arm. This new cybernetic arm could have special powers, like being able to detect dark magic. It would change the way he interacts with the magical world and his dueling techniques.
It could be a rogue wizard who is jealous of Harry's new cybernetic abilities. This wizard might think that Harry is polluting the purity of magic with technology and decides to stop him at all costs.
Another feature is the new plotlines it can create. It can take the familiar characters from the Harry Potter series and put them in situations that are completely different. For instance, instead of fighting Voldemort in the traditional way, they might have to battle a cybernetic - controlled dark force that is threatening Hogwarts. This makes for very exciting and fresh stories.
One popular cybernetic Harry Potter fanfiction is 'Cybernetic Magic in Hogwarts'. It combines the magical world of Harry Potter with cybernetic elements in a really interesting way. The main character discovers a hidden chamber that contains ancient cybernetic devices which have a connection to the magic in the school.
One interesting concept could be the integration of magic and cybernetics. For example, wizards might use cybernetic enhancements to boost their magical abilities. Maybe a wand could be modified with cybernetic parts to have more precise spell - casting. Another concept could be cybernetic creatures in the Harry Potter universe, like a mechanical Hippogriff or a robotic house - elf. These could add a whole new dimension to the magical world.
Characters can interact with both by using cybernetic devices to enhance their magic. For example, a cybernetic glove that helps a wizard better control the flow of magic when casting spells. They can also use magic to power or repair cybernetic parts. A simple spell could fix a malfunctioning cybernetic limb. Another way is by creating hybrid objects, like a magic - infused cybernetic broom that can fly faster and perform tricks that a normal broom can't.
Well, Harry could marry one of the veelas. Given their beauty and allure, it would add an interesting dynamic to the story. Their relationship could involve Harry having to deal with the jealousy of other wizards and also the cultural differences of the veelas. Or he could marry a descendant of one of the founders of Hogwarts. This would tie in a lot of Hogwarts history into their relationship, and their wedding could be a grand event that unites different factions within the wizarding community who have ties to the founders.
Maybe Dumbledore, if he were still alive in the fanfiction. Dumbledore was highly respected and had a great influence. Knighting Harry would be a way for him to publicly recognize Harry's achievements and heroism on a grand scale.
Hermione Granger is a very common character. Since she is Harry's best friend, she would likely be there to help him understand and control his new superpowers. She might research in the library to find out how these powers came about and how to use them effectively. Ron Weasley is also common. He would probably be both in awe and a bit jealous of Harry's new powers at first but would still support him in the end.
It could be Voldemort. He might use hypnosis as a new way to get to Harry, trying to make him a weapon against the Order of the Phoenix. Another possibility is a new dark wizard who wants to make a name for himself by controlling Harry Potter.