Leah could be a new ninja from a far - off land that has unique abilities. Maybe she has the power to control time or something really extraordinary.
Leah could also be a non - ninja character who accidentally gets involved in the ninja world. For example, she could be a healer who has no combat skills but has a great knowledge of herbs and medicine. Naruto meets her when he's injured on a mission and she nurses him back to health. This starts their connection and from there, their relationship, be it friendship or more, begins to develop.
Without more context from the specific fanfiction, it's hard to say exactly who Leah is. She could be an original character created by the fanfiction writer, perhaps someone with special powers or abilities.
One possible plot is that Leah is from a different village and she comes to Konoha. Naruto is assigned to show her around. At first, Naruto is his usual boisterous self and Leah finds it annoying. But then they discover a common enemy that is threatening both their villages. They then combine their unique skills, Naruto's Rasengan and Leah's special elemental magic (assuming she has some in this fanfic), to defeat the enemy and in the process, fall in love.
They could also be characters from an existing story or series that the fanfiction is based on. Maybe they were minor characters in the original and the fanfiction writer decided to give them a more in - depth relationship and the moment of the kiss to explore their potential.
It could be a new vampire character created specifically for the fanfiction. Maybe a young and somewhat rebellious vampire who doesn't fully adhere to the traditional vampire ways.
Jacob and Leah are the main characters. Jacob is known for his wolf - shifting abilities and his strong ties to his tribe. He's often conflicted in his relationships. Leah, she's a strong - willed female shape - shifter. She has to deal with the fact that she's different from the other male shifters in some ways. In the fanfiction, these two are the focus. Their interactions, whether it's them arguing about tribe matters or slowly growing closer, are what drive the story forward.
Well, it could be that Leah, for some reason, has a strong mental or emotional connection (the imprinting) with Naruto. Maybe she sees his determination and is drawn to it. She might start to follow his ideals and even develop a friendship or more with him in the fanfiction world.
One common theme is the clash and then the fusion of different worlds or cultures. Since Naruto is from his ninja world and Leah is from her own fictional setting, often there's a lot of exploration about how their different ways of life interact. For example, Naruto's ninja code versus Leah's moral values.
It could be one of the werewolves in her pack. Maybe someone she had a secret relationship with.
It could be an ex - partner of either Leah or Jasper. For instance, if Jasper has an ex - girlfriend who is jealous of Leah and the new baby, she might try to cause trouble between them. Maybe she spreads false rumors about Leah to make Jasper doubt her.
Leah was one of the wives of Jacob in the Bible. She was the older daughter of Laban. Leah was not as favored by Jacob as her sister Rachel at first, but she was still an important figure in the family. She had many sons, which was highly valued in that patriarchal society.