Well, perhaps there could be a plot where the virus is actually a dark magic - created plague. The Ministry of Magic is in chaos as they try to deal with it, and it's up to Hermione to research and find a solution using her vast knowledge of magic. Or maybe the virus is spreading among the Muggle - borns first, and Ron has to deal with his family's concerns while also trying to help his Muggle - born friends. There are many directions it could go depending on the creativity of the author.
In some fanfictions, the plot might involve the magical creatures being affected by the virus in different ways. For instance, the Hippogriffs might be carriers but not affected, while the house - elves start getting sick. Harry and his friends then need to figure out how to stop the spread among the creatures and also use their unique abilities to find a cure. This could lead to some really interesting interactions between the characters and the magical world around them, as they have to navigate both the virus situation and the relationships with the magical beings.
Perhaps Harry discovers that he has basilisk blood in him. This could change his abilities and how others view him. He might face discrimination from some in the wizarding world who fear the basilisk's power, while others might see him as a potential weapon against Voldemort. The plot could revolve around Harry coming to terms with this new aspect of himself.
One possible plotline could be that Harry, as a cyborg, uses his mechanical abilities to enhance his magic. For example, he might have a built - in spell - enhancer in his robotic parts that allows him to cast more powerful spells. Another could be that he has to hide his cyborg nature from the wizarding world at first, fearing they will reject him, but then uses it to fight a new kind of dark force that is immune to normal magic.
One possible plotline could be that the wizarding world has its own version of cops. Harry Potter and his friends could join this force and use their magic to solve magical crimes that the regular Aurors can't handle. For example, they might deal with dark wizards who are using new and undetectable forms of dark magic.
A plotline could involve an Uchiha character from the Naruto world being sent to the Harry Potter universe. This Uchiha could befriend Harry and teach him some of the Uchiha techniques, like how to enhance his senses or use some basic ninjutsu. Harry, in turn, could introduce the Uchiha to magic. Together, they could face threats in the wizarding world, like a new dark wizard who is immune to normal magic but vulnerable to ninja techniques.
One possible plotline could be Harry using his newfound baron status to reform the wizarding world's social structure. He might try to bring more equality among pure - bloods, half - bloods, and Muggle - borns. Another could be him having to deal with the political intrigue that comes with being a baron, like rivalries with other noble wizarding families.
Maybe Harry, as a politician, has to deal with the aftermath of the war. He could be trying to unite different factions within the wizarding community that were divided during the battle against Voldemort. He might face opposition from traditionalist wizards who don't want to see the changes he is proposing, such as equal rights for house - elves or better integration of muggle - borns into the wizarding society. And he would have to use his charm and the respect he has earned from his heroic deeds to convince others to support his political agenda.
Perhaps in this fanfiction, there is a spell gone wrong that merges Harry Potter with Alucard. Harry now has to deal with the new instincts and powers that come with being part - Alucard. He has to hide his new identity from his friends at Hogwarts while also trying to figure out how to use his combined powers to protect the wizarding world. There could be a sub - plot where some of the Hogwarts faculty suspect something is different about Harry and start to investigate, adding to the tension and drama of the story.
One possible plotline could be that Harry discovers he has Lamia heritage. This could lead to him having different magical abilities related to Lamia, like the power to charm or hypnotize. He might face discrimination from some in the wizarding world who fear the unknown Lamia powers.
One possible plotline could be that Harry discovers a zanpakuto in the Forbidden Forest. He has to learn how to use it while still dealing with the threats from Voldemort. Maybe the zanpakuto has some special powers that can help him in his fight against the Dark Lord.
One possible plotline could be that Harry discovers he has Nephilim blood. This newfound heritage gives him powers beyond what normal wizards have, and he has to struggle with how to control and use them while still fitting into the wizarding world. He might face discrimination from some wizards who fear his new abilities.