Maybe a new character that was introduced into the story specifically for this plotline. This new character could bring a lot of mystery and new storylines related to the pregnancy.
One possible plot twist could be that Tani Rey discovers she's pregnant during a really challenging time in her life, like when she's in the middle of an important mission. This would add a whole new layer of drama as she has to balance her personal situation with her duties.
Maybe it's a new character created specifically for the fanfiction. A powerful Jedi or a mysterious figure from a far - flung planet who crosses paths with Rey and through some intense and unexpected events, becomes the father of her unborn child.
It could be Finn. They have a strong bond in the movies, and it would be an interesting dynamic to explore their relationship as they prepare for a child together.
Maybe it's a completely new character introduced in the fanfiction. This new character could have some special powers or a unique connection to Naruto that results in the pregnancy.
It could be Beast Boy. Their relationship in the original series has some chemistry, and in the fanfiction, it would be an interesting twist if he were the father. Maybe their relationship takes a new turn when Raven discovers she's pregnant.
Perhaps it's a new kind of monster that was created through a combination of human technology and some ancient, unknown force. This new monster mated with Godzilla in some unexpected encounter, and now she's pregnant. There could be a whole backstory about how this new monster came to be and how it interacted with Godzilla.
It could be Rick. They have a strong bond and connection in the series, so it's a possibility that he could be the father in the fanfiction.
If we follow the more traditional route, Mako could be the father. They had a relationship in the show, and it would be a natural progression for them to start a family. Their relationship had its ups and downs, and the pregnancy could be a new chapter in their story together.
While Peeta is the obvious choice, some fanfictions might explore the idea of Gale being the father. This could add a whole new layer of drama and conflict. Maybe there was a moment of passion between Katniss and Gale before she fully committed to Peeta, and this led to her pregnancy. However, this would be a more controversial take as it goes against the main narrative of Katniss's relationship with Peeta in the original series.
It could also be a new character introduced in the fanfiction. Maybe a powerful demigod from another camp who Annabeth meets during a diplomatic mission. This would create a whole new set of drama and conflict, as Annabeth would have to deal with her feelings for Percy and this new person, as well as the implications of having a child with someone other than Percy.