One common theme is the struggle of balancing ninja duties and fatherhood. Naruto has to be out there protecting the village but also be there for his child.
One common theme is the struggle of single parenting. Naruto has to handle all the responsibilities of raising a child alone, like providing for them, protecting them, and teaching them right from wrong. Another theme is the clash of different worlds. Since it's a crossover, there are elements from different anime universes that Naruto has to deal with while raising his child.
Another theme is growth. Naruto grows as a person and as a father. He learns new things about himself and about parenting. He might start out not knowing how to make a proper meal for his child but by the end of the fic, he's a master chef for his little one. There's also the theme of protection. Naruto will do anything to protect his child from harm, whether it's from other ninjas or just normal everyday dangers in the village.
One common theme is legacy. Writers often explore how Minato's actions and reputation as a great shinobi left a mark on Naruto. Another theme is redemption. Maybe Minato feels he has to make up for not being there for Naruto when he was growing up. Also, the theme of discovery is popular, like Naruto finding out more about his father and understanding himself better in the process.
One common theme is passing on values. Naruto, as a father, often tries to pass on the ninja values he learned, like loyalty and hard work, to his children. Another theme is family balance. Since he is also the Hokage, he has to balance his duties to the village with his family responsibilities. And of course, there's the theme of protection. Naruto will do anything to protect his family from threats.
One common theme is redemption. Draco is often shown trying to atone for his past actions by being a good father. Another theme is the struggle against prejudice. People in the wizarding world may still have a negative view of him, but he has to rise above it for his child.
There is also the theme of overcoming challenges. Percy as a single father has to face various difficulties, such as financial problems if his partner was the main earner before, or dealing with the child's emotional problems due to the absence of one parent. These fanfictions often show how he overcomes these challenges with determination and love for his child.
One common theme is sacrifice. James has to sacrifice his own desires and time to focus on raising Harry alone. Another theme is love. His love for Harry is unconditional and drives him to do whatever it takes to protect and raise him well.
One common theme is sacrifice. Tony often has to sacrifice his time as Iron Man to be there for his child. For example, in many fics, he misses important Avengers meetings because his child is sick or has a school event.
One common theme is the struggle to balance the demigod world and normal parenting. Percy has to protect his child from mythological threats while also ensuring they have a normal childhood like going to school, making friends. Another theme is the passing on of values. Since Percy has his own set of values from his own adventures, he tries to pass those on to his child. And there's often the theme of loneliness too. Being a single father in a world where most people don't understand the demigod situation can be isolating.
One common theme is sacrifice. Harry often has to sacrifice his own desires or time for his child. For instance, he might give up on a dangerous but exciting adventure to be there for his kid's first day at Hogwarts.