A plot twist could be that the pregnancy is a false alarm. It was actually an elaborate prank by some mischievous ninjas. Naruto initially believes he's pregnant and starts to adjust his life accordingly. But then he discovers it was all a joke, and he has to deal with his mixed emotions of relief, anger, and embarrassment.
Maybe the 'pregnancy' is a sign of a new and unknown ninja power awakening within Naruto. It looks like pregnancy on the outside, but in reality, it's his body's way of preparing for a major power - up. This would change the story from a pregnancy - centered one to one about Naruto exploring and mastering this new power while dealing with the misunderstandings of those around him.
Another plot twist could be that the pregnancy progresses at an extremely abnormal rate. This could put Renesmee's life in danger and force her and her loved ones to find a way to slow it down or deal with the consequences of a very rapid development. It could also lead to some unexpected revelations about her own nature and abilities.
One plot twist could be that the 'pregnancy' actually turns out to be a way for Kyuubi to transfer its remaining power to Naruto in a more permanent and extreme way. Instead of just lending power, it's like a total fusion of their essences. Another could be that the 'pregnancy' is a ruse by an enemy who has manipulated Naruto's connection with Kyuubi to make it seem like this is happening, when in fact they are trying to steal the power that would be created from such a union.
A possible plot twist is that the goddess was actually cursed before getting pregnant, and the pregnancy is part of a larger scheme to break the curse. Percy has to go on a dangerous quest to find the antidote or solution to save both the goddess and the unborn child. It could also turn out that the child is prophesied to be a great hero or a great danger, leading to different factions trying to influence the outcome.
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.
One plot twist could be that the pregnancy is part of an experiment by the evil scientists again. They might be using it to study the growth and abilities of the half - human, half - bird hybrids. Another could be that the father of the baby is someone unexpected, like a character who was thought to be an enemy but turns out to have a different side.
One possible plot twist could be the discovery of some hidden power in their unborn child. In the world of Percy Jackson, powers are often unexpected. Maybe the baby has a unique ability related to both Annabeth's wisdom and Percy's water - controlling powers. This could lead to various adventures as they try to protect the baby from those who might want to use its power for evil.
One possible plot twist could be that Robin discovers he has some magical heritage that affects the pregnancy in an unexpected way. Maybe his magic interacts with Regina's and causes strange things to happen during the pregnancy, like the baby having unique powers from the start.
In a 'naruto gets pregnant fanfiction', perhaps there is a powerful enemy who casts a spell on Naruto. This spell not only endangers his life but also has the side - effect of making him pregnant. The story could then revolve around Naruto trying to find a way to reverse this while also dealing with the reactions of his friends and the village.
One possible plot twist could be that Naruto is not actually the real target. Maybe Pein was misinformed and Naruto has a secret twin or something. Another twist could be that Pein is being controlled by an even greater evil, and kidnapping Naruto is part of a larger scheme to take over the ninja world. Or perhaps Naruto has some hidden power that he himself doesn't know about, and Pein kidnaps him to try and unlock that power for his own use.
One possible plot twist could be that the father of Maria's baby is not who she initially thought. Maybe there was some sort of mix - up at a fertility clinic or she was deceived by someone she trusted. Another twist could be that Maria discovers she has some sort of alien - related pregnancy, given the Roswell theme, which could bring in all sorts of strange powers or abilities for the unborn child. A third twist might be that Maria decides to keep the pregnancy a secret from most of the people in Roswell, but as she tries to hide it, she gets into all sorts of comical and tense situations.