Well, perhaps Sonic is cursed by an evil wizard to turn into a vampire. In this story, he might have to find a way to break the curse before it's too late. He could encounter other vampire characters who either try to help him or lead him astray. His transformation could also give him new abilities that he has to learn to control, such as the power of flight or the ability to hypnotize enemies, which would add an interesting twist to his usual battles.
One possible plotline could be that Sonic gets bitten by a vampire during one of his adventures in a spooky zone. He then starts to notice changes in himself, like a craving for blood and enhanced speed at night. His friends initially don't realize what's wrong and think he's just acting strange. As he turns more vampiric, he has to struggle with his new nature and not harm his friends.
In a Sonic - turned - vampire fanfiction, it could start with Sonic exploring an ancient castle. There, he disturbs an old vampire who was in slumber. The vampire attacks him and turns him. Sonic's friends, Tails and Knuckles, start to notice his paler complexion and his avoidance of sunlight. Sonic has to deal with the fact that he can no longer eat his favorite chili dogs in the same way. He also has to face off against new vampire - related enemies that are drawn to his new vampire energy. He may even have to journey to a vampire realm to seek a cure, all while trying to keep his vampirism a secret from his friends who might fear or reject him if they knew.
One possible plotline could be that Henry Lau, after turning into a vampire, struggles to come to terms with his new identity. He might try to hide it from his friends and family at first. For example, he could be a famous musician in his human life, and now he has to find ways to continue his career without revealing his vampiric nature. He may have cravings for blood that he tries to resist, leading to internal conflicts.
One possible plotline is that Bella uses her new - found power to seek revenge on those who once threatened her or her loved ones. Another could be that she tries to unite different vampire groups with her power and charisma. Maybe she discovers a hidden vampire ability that no one else has and uses it to change the vampire world for the better.
One possible plotline is that they meet due to a dimensional rift. Sonic is zapped into Rainbow Dash's world and they have to work together to find a way to send Sonic back. Along the way, they encounter various threats and have to use their combined skills to overcome them.
One possible plotline could be Sonic struggling to come to terms with his new robotic parts. He might face challenges in his speed or his usual acrobatic abilities and have to relearn how to move and fight. For example, his robotic parts could malfunction at crucial moments.
One possible plotline could be that Sonic is facing a new and extremely powerful villain who manages to outwit him in a battle and ultimately kill him. This could lead to his friends, like Tails and Knuckles, vowing revenge and setting out on a journey to become stronger to face the villain.
One possible plotline could be that some sort of magical or scientific accident causes the two universes to collide. Sonic, while exploring the new world he has been thrown into, meets Twilight Sparkle. As they try to figure out how to get Sonic back to his world, they develop an unlikely bond that leads to a kiss. Another could be that an evil force is trying to take over both their worlds and they team up. During their adventures together, feelings develop and they end up kissing as a symbol of their new - found connection.
One possible plotline could be that Naruto discovers a hidden vampire world while on a mission. Maybe he stumbles upon a vampire lair and has to figure out how to deal with these new, powerful creatures. He could be intrigued by their powers and try to learn from them while also keeping his own ninja village safe from any vampire threats.
A common plotline might be that the vampire girlfriend has special powers that Naruto needs to defeat a powerful enemy. For example, her ability to control blood could be used in a creative way in battle. Also, there could be a plotline where their relationship is forbidden because of her being a vampire and Naruto being a ninja, and they have to fight against the norms of their respective worlds to be together. This would involve them facing opposition from both the ninja community and any vampire clans that exist in the fanfiction.
Another possible plotline is that Valerie and Stefan discover a hidden prophecy that links their fates together. They then have to work together to fulfill the prophecy or prevent it from coming true. Along the way, they face numerous obstacles and their relationship is put to the test. Their journey could take them to different magical realms or involve battles with powerful supernatural beings.
In a 'Jon Snow is a Vampire' fanfiction, the plot could start with his death and subsequent resurrection as a vampire. This new form could make him an outcast, even more so than he was before. He might have to journey to find a way to reverse his condition. Along the way, he meets old friends and enemies who react differently to his vampiric state. Some might fear him, while others might see him as a powerful ally. His relationships with his Stark siblings could be severely tested as they grapple with the fact that he's no longer fully human.