There could be original characters created specifically for the fanfiction. For example, a wizard who has some knowledge about the origin of the Omnitrix and tries to guide Harry. This character could be an old hermit - like wizard who has been studying interdimensional objects for years. Also, there might be a villain who is after the Omnitrix, someone who wants to use its power for evil purposes and constantly hunts Harry down.
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.
In this fanfiction, Naruto might use the Omnitrix to gain various alien forms' powers. He could use those powers to fight stronger enemies in the Naruto universe, like the Akatsuki members. Maybe he would use the powers for stealth or super strength depending on the alien form.
In a Percy Jackson has a Omnitrix fanfiction, the plot could involve Percy being sent on a special mission by Chiron. During this mission, he stumbles upon the Omnitrix. He soon discovers that the Omnitrix has some sort of connection to the Greek gods. As he uses it to transform into various alien forms, he finds that each form has a unique ability that can either help or hinder him in his quest. For example, one form might be able to swim super fast in the ocean, which is great for underwater battles, but another form might be weak against fire, which could be a problem when facing a fire - breathing monster. Along the way, he has to learn to balance his use of the Omnitrix with his own demigod skills and knowledge of Greek mythology to succeed in his mission.
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.
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, 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.
Well, for example, Natsu's fire - dragon slayer magic could potentially interact with a heat - based alien form from the Omnitrix. Maybe when he's in that form, his fire magic becomes even more intense or has a different quality to it. He could use his dragon slayer skills to control the heat in a more precise way than the alien form normally allows.
Obviously, Naruto would be one of the main characters since he has the Omnitrix. But we could also expect to see his usual friends like Sasuke and Sakura. They would be involved as Naruto uses his new powers. And perhaps some of the alien forms from the Omnitrix could be considered 'characters' in a way, as they would influence Naruto's actions and decisions.