One common theme is redemption. For example, Deidara, who was initially a villain, might find a path to redemption through his connection with Naruto's family. Another theme is acceptance. Naruto's family and friends might have to accept Deidara, who has a very different background and set of values.
A great one is 'Deidara's New Family with Naruto'. In this story, after a series of unexpected events, Deidara finds himself in a situation where he has to rely on Naruto and his friends. It gradually builds a family - like relationship between them. The author does a great job of showing the character development of both Naruto and Deidara as they navigate this new relationship.
In some fanfictions, Deidara might give Naruto training on explosive jutsu control. Since Deidara is known for his explosive clay techniques, he could potentially teach Naruto how to better handle and utilize explosive elements in combat.
In a fanfiction, Deidara and Sasori could be sent on a secret mission to infiltrate a hidden village. Deidara uses his clay creations to distract the guards while Sasori sneaks in with his puppets. As they progress, they discover a powerful weapon that the village is developing. They then have to decide whether to destroy it or take it for the Akatsuki. Along the way, they also have to deal with their own internal conflicts and the pressure of the mission.
They could be on a journey to find a rare material for Deidara's art. Sasori, with his knowledge of the ninja world, helps guide them. Along the way, they encounter various strange creatures and ninja clans. They might have to fight off some who are after the same material.
There's a fanfic called 'Deidara's Redemption in Naruto's World'. In this story, Deidara has a change of heart after multiple encounters with Naruto. It delves deep into how Naruto's unwavering belief in the good of others starts to affect Deidara and his view of the ninja world.
One idea could be that they discover they are brothers in a hidden past plot twist. Maybe their parents were from different villages but fell in love secretly. As brothers, they could team up to face a new and powerful enemy that neither could defeat alone.
In this fanfiction, their brotherhood might lead to a cultural exchange between Iwa and Konoha. Naruto could introduce Deidara to Ichiraku Ramen, and Deidara could show Naruto some unique Iwa traditions. As they do this, they also have to face some who oppose their new relationship, thinking it might be a threat to the balance of power between the villages. But they prove everyone wrong with their strong bond and how they use their combined skills to protect both villages.
Their family background could be really complex. Maybe their parents were shinobi from different villages who fell in love during a time of peace. But then something happened, like a war broke out between the villages, and they were separated. Naruto was left in Konohagakure, and Deidara was taken to Iwagakure. Their family could have had a strong ninja lineage, which explains their powerful abilities.
Often, these fanfictions focus on the complex relationship between the two characters. They might explore the contrast in their personalities, like Naruto's optimism and Deidara's more artistic and explosive nature. This contrast can create interesting dynamics in the story.