To start a fanfic about Naruto and Hinata making Boruto, first think about the setting. You could begin with a simple family scene at home in Konoha. Maybe Naruto is just back from a mission and Hinata is preparing dinner while Boruto is showing Naruto his new ninja moves. Then, start writing down their dialogues. For example, Naruto could be saying how proud he is of Boruto's progress. Keep it simple and build on their relationships as a family.
I don't think there would be a lot of fanfiction like that. Hinata has always been loyal to Naruto. In the Naruto universe, their relationship is based on a lot of development and mutual understanding. So it's hard to imagine a scenario where Hinata would cheat on Naruto with Boruto in a legitimate fanfiction.
Friendship also plays a big part. Boruto's friendships at the academy and how his parents' experiences with friendship influence him. Fanfics might show how Boruto helps his friends using the lessons he learned from Naruto and Hinata's stories about their own friends.
Websites like FanFiction.net and Archive of Our Own (AO3) are great places to start. They have a large collection of fanfics related to Naruto and his family.
There are many fanfics that explore the relationship between Naruto and Hinata further. Some might focus on their daily family life with Boruto and Himawari, like how they deal with Boruto's rebellious phase while still maintaining a loving family environment.
There's a fanfic called 'Boruto's Training with Naruto and Hinata'. In this one, Boruto gets special training from both his parents. It delves into how Naruto's teachings differ from Hinata's and how Boruto grows from it. It also has some really cool action scenes where Boruto uses new jutsus he learned from them.
One idea could be to focus on their anticipation and preparation for the baby. They might discuss names, decorate the nursery, and Hinata could be shown getting advice from her family. Naruto, on the other hand, would be excited but also a bit nervous about becoming a father.
One plot idea could be Boruto getting lost in a mysterious forest during a training exercise. Naruto and Hinata then team up to find him. Along the way, they face some old enemies or new threats that test their skills and their relationship as a couple. Another idea is that Boruto discovers a hidden power within himself that Naruto doesn't understand, and Hinata has to be the one to bridge the gap between father and son by helping Naruto understand Boruto's new ability.
Well, there's this fanfiction titled 'Hinata's Influence on Boruto'. It delves deep into how Hinata's gentle nature and strong values shape Boruto's character as he grows. It has some really heart - warming scenes between mother and son. And then there's 'Boruto's Path to Greatness' which also involves Naruto and Hinata in the background, guiding Boruto on his ninja journey.
One idea could be a story where Boruto and Himawari discover an old diary of Naruto's from his early days as a ninja. Hinata helps them understand the context and the values their father held. They then use those lessons to face a new threat in the village.