One unique plot might be that the baby is born with a prophetic ability. The fanfiction could be about how Naruto and Sakura try to understand and manage this ability, while also dealing with the political implications within the ninja world. Since many might want to use the baby's power for their own purposes. It could be a complex story of power, family, and loyalty.
Maybe the baby in the fanfiction is kidnapped by a rogue ninja group. Naruto and Sakura then embark on a dangerous journey to rescue their baby. Along the way, they face many challenges and also learn more about each other and their relationship. This plot would be full of action, adventure, and emotional moments as they fight to get their baby back.