Well, he might gain the ability to regenerate like a phoenix. Just imagine, if he gets injured in a battle, instead of being seriously hurt, he could rise from the ashes, so to speak, and be back in action quickly.
If Harry Potter becomes part phoenix in fanfiction, it could also change his appearance. He might have some phoenix - like features, such as feathers in his hair or a more fiery look in his eyes. His personality could also be affected. Phoenixes are known for their loyalty and courage, and Harry already has those traits, but they could be intensified. This could make him an even more formidable wizard and a greater leader in the fight against evil.
Well, if Harry Potter becomes a Phoenix Animagus in fanfiction, he would gain some really cool abilities. For example, he could regenerate from ashes like a phoenix. He might also have the power of flight, which would be a huge advantage in battles or just for getting around quickly. His connection to magic could become even stronger as the phoenix is a very magical creature. And he could use his new form to spy on the Death Eaters without being detected easily.
If Hedwig was a phoenix in fanfiction, she could have the power of rebirth. So, if she were ever in danger or killed, she could rise from the ashes. This would add a whole new level of drama and protection for Harry. Also, phoenixes are associated with magic and prophecy, so Hedwig might be able to give Harry more insights or warnings.
In some fanfictions, if Harry Potter becomes a warlock, he might gain even more powerful magic. He could have greater control over spells and be able to perform magic that was previously thought impossible. For example, he might be able to manipulate time in a more complex way or have the power to instantly transport himself anywhere in the wizarding world without the need for a Portkey or Apparition.
If Harry Potter becomes god in fanfiction, he might completely reshape the magical world. He could rewrite the laws of magic, perhaps making it more accessible and less dangerous. He could also bestow extraordinary gifts upon his friends. Hermione might gain the ability to instantly understand and master any spell or bit of knowledge, and Ron could become an unbeatable warrior with superhuman strength in the face of any danger.
In this kind of fanfiction, Harry might teach his children magic in a very different way from how he was taught. He would be extremely protective, having faced so many dangers himself. Maybe he'd pass on the lessons he learned from his own battles, like the importance of friendship and courage.
If Harry Potter becomes the Joker in fanfiction, he would probably start to question all the values he once held. The Joker is all about subverting order, so Harry might begin to undermine the Ministry of Magic and other institutions. He could use his knowledge of magic to play cruel pranks on people, not the innocent kind of pranks he used to do. His Gryffindor courage could be twisted into a reckless disregard for the safety of others.
If Harry Potter becomes a Jedi, he would likely combine his existing magical skills with Jedi abilities. His Patronus charm could be enhanced by the Force, becoming an even more powerful protective entity. He might use his wand as a sort of lightsaber hilt, channeling the Force through it for unique combat moves. His ability to apparate could be refined with Jedi - like teleportation skills. Also, his knowledge of the wizarding world's dark magic could help him better understand the dark side of the Force and avoid its temptations.
If Harry Potter becomes a Lamia in fanfiction, his relationships would change drastically. His friends might be both intrigued and a bit scared at first. He would have to adapt to his new form and its characteristics. For example, he may need to learn how to control any new instincts that come with being a Lamia. Also, his role in the fight against Voldemort could be completely different. Instead of using a wand in the traditional way, he could use his Lamia - related powers to combat the dark forces.
If Harry Potter becomes a demon in fanfiction, his relationships would be severely affected. His friends like Ron and Hermione would be very confused and possibly afraid of him. They might try to find a way to reverse the transformation. And Hogwarts itself would be in chaos. The teachers would be divided on how to deal with him, some might want to help him while others might see him as a threat to the safety of the school.
Well, it would be a total chaos. He might use his magic skills to cause destruction. For example, he could turn Hogwarts into a dark fortress and rule over it with an iron fist. His friends would be shocked and probably try to stop him, leading to some really intense battles.