Well, it would be really interesting. Percy is used to his own world of Greek gods and demigods. If he became a Cullen, he'd have to adapt to the vampire lifestyle. He'd probably bring his combat skills and his sense of loyalty. Maybe he'd be the one to protect the Cullens in a different way than they're used to. He might also struggle with the whole not - eating - people thing, since he's used to having his own diet in his world.
If Percy Jackson becomes a Cullen in fanfiction, first of all, his powers would be a strange addition to the Cullen family. His water - controlling abilities could be used in new and unexpected ways in the vampire world. He could potentially use water to create barriers or distractions. Also, his relationship with other characters would change. He'd have to deal with the Cullens' complex family dynamics. His impulsive nature from his demigod life might clash with the more reserved nature of the vampires at times.
In a fanfiction where Percy Jackson becomes a Cullen, his transformation would likely cause a stir. The Cullens are known for their elegance and restraint, while Percy is more of a rough - and - tumble hero. His entry into their world could introduce new ideas and values. For example, he might encourage them to be more proactive in protecting humans instead of just staying on the sidelines. His presence could also attract unwanted attention from other supernatural beings who are either curious about this new 'hybrid' or see him as a threat. And he would definitely have to figure out how to use his demigod powers within the limitations of being a vampire.
If Percy Jackson becomes a singer in fanfiction, he could attract all kinds of audiences. Demigods would surely come to his shows, curious to see how he expresses his dual identity through music. He might also gain a following among mortals, who are drawn to his otherworldly charm and the stories his songs seem to tell.
Well, he would probably be an amazing soldier. Given his skills from his demigod adventures, like his combat abilities and quick thinking. He could use his sword - Riptide - to great effect. Maybe he'd be part of a special unit in the fanfiction, using his powers to protect his comrades and take on dangerous missions.
Well, if Percy becomes a wolf in fanfiction, he would probably have to adapt to a whole new way of life. He'd be part of a wolf pack perhaps. This could lead to some interesting character development as he learns the pack's hierarchy and how to communicate in a more primal way. And his relationship with his friends might change too, as they might be a bit wary of his new wolfish form at first.
If Percy Jackson were to become Lucifer in fanfiction, it could lead to some really interesting storylines. He could use his new Lucifer - like status to rebel against the gods in a different way than he did as Percy. His view of the world would change drastically. For example, he might no longer see the Olympian gods as the ultimate authority. Instead, he could try to create his own order or chaos, depending on how the author interprets the Lucifer character.
In fanfiction, if Percy Jackson becomes a primordial, it would be a huge shift in the narrative. He could be involved in the creation or destruction of new worlds. His personality might also change. He could become more detached, like many primordial beings are, as he now views the world from a much higher and more complex perspective. He might have to make decisions that affect the entire fabric of existence, and his actions would have consequences on a universal scale.
If Percy Jackson becomes the Joker in fanfiction, it would be a really wild and unexpected transformation. The story could take a very dark turn. Percy, who is usually a heroic figure, would now have the chaotic and unpredictable nature of the Joker. His friends in the Percy Jackson universe might not recognize him, and he could start causing all sorts of mayhem in both the demigod world and the mortal world. Maybe he'd use his newfound Joker - like insanity to play cruel tricks on his former allies or enemies, blurring the lines between good and evil even more in the fanfiction world.
In some fanfictions, if Percy Jackson becomes Death, he might gain the power to decide the fates of all beings. He could be seen as a very solemn and powerful figure, no longer the carefree demigod. His relationships with other characters would also change drastically. For example, his friends might fear him at first, but then come to understand his new role and the importance of it in the grand scheme of things.
Well, he might gain enhanced physical abilities like super strength, speed, and agility. His senses would also be heightened, which could make him an even more formidable opponent. He'd probably have to deal with the whole moon - influenced transformation thing too, which could be both a curse and an advantage depending on the situation in the fanfiction.
Well, he'd probably bring his own heroic style to the role of Doctor Fate. Percy is used to fighting with a sword and his demigod powers. As Doctor Fate, he might combine his water - controlling abilities with the magic of Doctor Fate's artifacts. He could make some really unique spells using his Poseidon - given powers.
In such a fanfiction, Percy might gain the power to manipulate time. He could go back in time to prevent disasters in the demigod world, like stopping Kronos from rising before. He might also be able to foresee future threats and prepare for them. For example, he could ensure the safety of Camp Half - Blood in advance against any upcoming attacks.