One possible plot twist could be that Sakura has to face opposition from the village elders. They might be skeptical of her ability to raise Naruto, given his status as a jinchuriki. Another twist could be that Naruto starts to show signs of his powerful chakra at a very young age, which makes it difficult for Sakura to control the situation.
Perhaps a major plot twist is that Sakura's adoption of Naruto is part of a larger prophecy. As she raises him, she starts to notice strange coincidences and signs that seem to point to Naruto being key to saving the ninja world in a way no one expected. This could put a huge burden on Sakura as she tries to protect Naruto and also prepare him for his future role, all while dealing with the normal challenges of raising a child.
One possible plot twist could be that Anko has a hidden power that Naruto uncovers during the adoption process. Maybe she has a connection to an ancient clan or a special jutsu that she's been suppressing. This discovery could change Naruto's view of her and also put them in danger as others might be after that power.
Maybe Naruto adopts Kakashi in a post - war scenario where Kakashi has lost his purpose. Naruto, seeing Kakashi's lost state, decides to take him under his wing. As a result, Kakashi starts to learn new jutsus from Naruto and they develop a bond that is more like brothers. This would be a great opportunity to explore their characters in a different dynamic.
The plot of a Naruto turns into Sakura fanfiction could involve Naruto experiencing Sakura's emotions more directly. He might feel the pressure she has always felt to keep up with Naruto and Sasuke. This could lead to him understanding her better and trying to change things when he turns back. Also, there could be a situation where Naruto - as - Sakura has to go on a mission alone. This would force him to fully embrace Sakura's skills and personality. He could end up using her intelligence and strategic thinking in ways he never thought possible, which would not only be a growth for the 'Naruto - in - Sakura' character but also an interesting exploration of Sakura's potential.
One possible plot twist could be that Itachi's past actions as a double agent in Akatsuki are revealed in a new light because of the baby. Maybe his enemies try to target the baby to get revenge on him, but Sakura, being a strong kunoichi, defends the baby with all her might. This could lead to a series of battles and alliances being formed in the shinobi world to protect the new life.
Another interesting plot twist could be related to the purpose of Naruto's transformation. Suppose Naruto transforms to save Sakura from a dangerous situation. But the transformation has some unforeseen side effects. For instance, he might lose control of his new powers temporarily. Sakura then has to find a way to help him regain control while also dealing with the threat that made him transform in the first place.
Well, they might join Akatsuki in fanfiction because they think they can change the organization from the inside. Naruto, with his strong belief in redemption, could believe that he can turn the Akatsuki members to the good side. Sakura, who always stands by Naruto, would follow him. Once inside, they would face a lot of challenges. The Akatsuki members are all very powerful and have their own motives. Naruto and Sakura would have to deal with the likes of Itachi and Kisame. Itachi might see through their plan, or they might actually start to understand Itachi's own complex situation and motives which could lead to a whole new set of developments in the story.
In such a fanfiction, perhaps Sakura sees Naruto's loneliness after all his friends have started their own families. Feeling responsible, she adopts him. She then helps Naruto to further his ninja career by training with him. They could go on missions together, and Sakura would be like a mother figure guiding Naruto in making important decisions in both his personal and ninja life.
Well, perhaps in the fanfic, their baby has some special ninja abilities from birth. Naruto and Sakura are both proud and a bit worried. They seek advice from their old friends like Kakashi. They train the baby in a new way that combines Naruto's Rasengan - like techniques and Sakura's brute strength. And they face challenges from enemies who want to use the baby's power for evil.
A possible plot twist is that the dads face legal issues all of a sudden. For example, some loophole in the adoption laws is discovered that puts the adoption in jeopardy. Or perhaps the baby girl has some sort of special ability or condition that they were not aware of at first, which completely changes the dynamic of their family life.
One possible plot twist could be that Naruto and Sakura are forced to betray their village under some kind of mind - control. Maybe an enemy has a powerful jutsu that can manipulate their thoughts and actions. So, they end up doing things that seem like a betrayal to their friends and comrades.