It might be an old acquaintance who she had a brief encounter with. This would create a lot of drama as Louisa has to figure out how to tell him, and he might have a very different reaction, perhaps being shocked or even initially denying any responsibility. The fanfiction could then explore how they come to terms with the situation.
There could also be a scenario where the father is a mystery. Louisa doesn't know who the father is, and she decides to raise the baby on her own. However, as the story progresses, she starts to get clues and suspects certain people. This would add an element of mystery to the fanfiction, with the readers also trying to figure out who the father might be along with Louisa.
In one scenario, it could be her long - time boyfriend. They've been together for a while, and the pregnancy is a natural step in their relationship. They are both excited and a bit nervous, and the fanfiction could focus on how they prepare for the baby together, like shopping for baby clothes and setting up the nursery.
In one scenario, the father could be another werewolf from her pack. It could be a relationship that was kept secret, and the pregnancy now forces them to come forward and deal with the consequences.
The father could also be a character who has some sort of special power or ability. For example, a wizard or a sea - spirit - like being. If the father was a wizard, the pregnancy could have some magical implications for the unborn child. And if it was a sea - spirit, there could be a connection to the ocean and the powers of the sea that the child might inherit, leading to a very unique and fantastical fanfiction story.
Another option could be Jesse. Their relationship was also quite intense. Jesse has his own ambitions in the world of performing arts, and a pregnancy with Rachel would create a huge conflict for him. He might be torn between his love for Rachel and his career goals, and this could lead to some really dramatic storylines in the fanfiction.
It could be Fitz. Given their complicated relationship throughout the series, a fanfiction could explore what would happen if they had a child together. Their political positions and personal feelings would add a lot of depth to the story.
In some fanfic ideas, it could be an unexpected character. Maybe a character from a different faction who she initially had a hostile relationship with but then circumstances changed. For example, a former raider who turned his life around and they fell in love, resulting in the pregnancy.
In one scenario, Nick could be the father. Given their on - again, off - again relationship, it would make for a really interesting story arc. Their relationship would be put to the test as they prepare to become parents. Another possibility could be Schmidt. Maybe there was a wild party night where things got a bit out of hand and he could be the father, which would create a whole lot of drama considering his relationship with Cece.
One possible plot could be Louisa dealing with the unexpected pregnancy while still trying to pursue her career dreams. Maybe she has to balance doctor's appointments with job interviews, creating a lot of comical and heart - warming situations.
One possibility could be Grayson. Given their on - again, off - again relationship in the show, it would make sense for him to be the father. Their relationship has always been complex, and a pregnancy would add another layer of drama.
Another possibility could be an old flame from Lorelai's past. Maybe someone she dated briefly before coming back to Stars Hollow. This would bring in a lot of drama and unresolved feelings. Lorelai would have to deal with the fact that this person is now back in her life in a very big way, and they would have to figure out how to co - parent.
In some interpretations, it could be another powerful ninja who has a secret relationship with Madara. Maybe it's someone from a rival clan, which would add a lot of drama and conflict. For example, if it were a member of the Senju clan, considering the long - standing feud between the Uchiha and Senju.