Perhaps a girl with psychic abilities. She can sense Jeff's presence before he even gets close to her. Instead of running away, she tries to communicate with him telepathically. This confounds Jeff at first, but he soon becomes intrigued. Her unique powers and her non - judgmental attitude towards him make her a great candidate for a love interest as they embark on a journey of understanding and love within the dark world of the fanfiction.
Another option could be a fellow 'dark' character. Let's say a female vampire who is also used to being feared and alone. They could meet in the shadows of the night and initially be wary of each other. But as they discover their similarities, like their thirst for something (Jeff for bloodlust and the vampire for blood), they start to form a bond that turns into a romantic relationship.
Well, one common character is a female love interest. She could be a strong - willed person who is initially scared of Jeff but then gradually falls in love with him. There might also be a sidekick - type character for Jeff, someone who has known him for a while and tries to warn the love interest about Jeff's true nature. And in some fanfictions, there could be a detective - like character who is trying to solve the mystery of Jeff's killings while also getting involved in the love story. This character might be suspicious of the relationship between Jeff and the love interest and tries to break them up for the sake of safety.
There could be his victims. They might not recognize him at first when he turns into a girl and he could use this to get closer to them. Another character could be a mysterious figure who either caused the transformation or is trying to help Jeff reverse it.
The kidnapped victim could be the main character. They would be the focus as they struggle against Jeff. For example, it could be a young girl who shows great courage throughout the ordeal.
Irene Adler could be a great love interest. She's smart, cunning, and was able to outwit Sherlock once. Their relationship in the original stories had a certain tension that could be developed into a full - blown love story in a fanfiction. She challenges him and has her own secrets, which could make for an exciting dynamic.
Sasori could be an interesting love interest. They are both from Akatsuki and have a certain connection through their art, though Sasori's is more in the form of puppets and Deidara's is explosive art. Their different personalities could create a lot of tension and a unique love story.
A foreign ninja from another village might also work well. This ninja could bring a different perspective to Kabuto's world. They could meet during a diplomatic mission or a joint training exercise between villages. Their love would be a bit more challenging as they have to deal with the politics between their respective villages, but it would add an interesting layer to the fanfiction.
A strong - willed priestess could be a great love interest. She could be the one who interprets the gods' will and at first is hesitant about Hercules due to his half - god status, but then falls for his heroism.
A person who could fall in love with Jeff might be a misfit in society. They don't fit into the normal norms and values, so they are attracted to Jeff's outsider status. This person could also be suffering from some form of mental illness that makes them empathize with Jeff's disturbed mind. They might believe that they can bring some light into Jeff's dark world. Maybe they have a fascination with the macabre and see Jeff as the ultimate expression of that. They are willing to overlook his murderous tendencies in the hope of a deep and unique connection.
A fellow Gryffindor Quidditch player would be a great love interest. They already share the passion for the sport and the house pride. They would understand Oliver's dedication to Quidditch and support his dreams. Another option could be a girl from Hufflepuff who is kind - hearted and loves to watch Quidditch. She could bring out Oliver's softer side. Or a Ravenclaw who is really smart and helps Oliver with strategies for his team, and they fall in love over their shared interest in making the Gryffindor Quidditch team better.
A historian would be a great love interest. She could be researching the events of his time and be fascinated by his story. Thackery, in turn, would be intrigued by her knowledge of his past and they could form a connection based on that shared interest.