Well, perhaps the Omnitrix gets mixed up with the magic in Hogwarts. It starts malfunctioning and instead of the usual alien forms, it gives Harry forms of ancient wizards. He has to figure out how to control these new forms while also dealing with the mystery of why the Omnitrix is acting this way. And he might learn new spells and magic from these wizard forms.
Hermione would be extremely curious. She would immediately start researching it, trying to figure out its mechanics and where it came from. She might even try to find a way to improve it or adapt it to the wizarding world's technology.
Well, he could use it to transform into different alien species and gain their powers. For example, he could turn into a strong and durable alien like Four Arms and be better at fighting Death Eaters. It would definitely change the whole dynamic of the wizarding world as his abilities would be a combination of magic and alien powers.
One possible interesting plot could be Harry using the Omnitrix to transform into various alien forms to battle dark wizards. For example, he might turn into a strong and durable alien to withstand powerful spells. Another plot could involve Harry trying to keep the Omnitrix a secret from his Hogwarts friends while still using it to his advantage in dangerous situations.
Sure. One idea could be that Harry discovers the Omnitrix during a trip to the Forbidden Forest. He initially has no idea what it is but as he experiments with it, he realizes its potential. He then uses it to secretly train himself, away from the prying eyes of his teachers and classmates. Another idea is that the Omnitrix is sent to him by an unknown wizard from a different dimension who thought Harry could use it to fight Voldemort more effectively.
One idea could be that a character from Fairy Tail finds the Omnitrix and has to learn how to use it without getting overwhelmed by its powers. Maybe they initially use it for simple tasks like getting out of tight spots during a guild mission, but as they get more proficient, they start using it in more complex battles against powerful foes.
One idea could be that the male OC with the Omnitrix accidentally gets transported to an alternate dimension where the Omnitrix functions differently. He has to figure out how to adapt and use it to get back home. Another plot could involve the OC using the Omnitrix to stop an alien invasion that is targeting his hometown specifically. Maybe the aliens are after the Omnitrix's power source.
A possible plot is that the self - inserted character has to deal with the Omnitrix malfunctioning. This could lead to unexpected and sometimes comical transformations. They might transform into a really weak alien in the middle of a battle or into an alien that is completely inappropriate for the situation, like a tiny alien when they need to be strong. As they try to fix the Omnitrix, they learn more about its inner workings.
One interesting plot idea could be exploring what would happen if Harry had a different upbringing, like being raised by the Malfoys. It would completely change his view of the wizarding world and his relationships. Another idea might be a time - travel fanfic where Harry goes back to the Marauders' era and interacts with his parents and their friends. This could lead to him preventing certain tragedies or changing the future in unexpected ways. And then there's the concept of a fanfic where the roles are reversed, and Voldemort is the one trying to protect the wizarding world from a greater evil, with Harry being the main antagonist.
In some Omnitrix fanfiction, there are crossovers with other universes. For instance, a story where the Omnitrix wielder ends up in the Star Wars universe. They have to use their alien forms to survive in this new and very different environment, facing off against Sith Lords and using their powers in creative ways to interact with the Force.
A great plot point might be Arwen's perspective on the concept of magic in the Harry Potter universe compared to that in Middle - earth. Since she has a different understanding of magic, her reactions and interactions with the wizards could be really fascinating. For instance, she might be surprised by some of the more 'brute - force' spells used in the wizarding world, while the wizards might be in awe of her more subtle and nature - based elven magic. Another interesting aspect could be if Arwen gets involved in the fight against Voldemort. Her elven wisdom and powers could potentially change the course of the battle in unexpected ways.