One possible reason could be a threat from Iwa to Konoha. If Iwa was planning an unprovoked attack on Konoha, Naruto might take it upon himself to destroy Iwa to protect his village.
Maybe there was some sort of evil force in Iwa that Naruto had to eliminate. For example, if there were rogue ninjas in Iwa who were causing chaos and harm not only to their own village but also to the surrounding areas, Naruto would step in and destroy the source of the problem which is Iwa in this case.
One possible reason could be a threat to Konoha. If Iwa planned an attack on Konoha, Naruto, as a defender of his village, might take the fight to them and end up destroying parts of Iwa in the process.
There might be characters from Iwa who oppose Naruto. For example, the Tsuchikage of Iwa would surely be involved as the leader of the village Naruto is attacking.
Maybe in the 'naruto neglected iwa fanfiction', there's a story where Iwa has a secret technique that could have been useful in the great ninja wars, but because they are neglected, they are not invited to share this knowledge. As a result, a young Iwa ninja goes on a journey to find a way to make the other villages recognize their worth and the importance of their techniques.
Sasuke could be involved. He and Naruto often have intertwined stories. Sasuke might either be an ally in Naruto's destruction of Iwa, or he could be there for his own reasons, like seeking power or revenge.
Naruto is obviously a very popular character in these fanfictions as he is the main character of the original series. In Iwa, characters like Deidara (who was originally from Iwa) often make appearances. His explosive jutsu and unique personality add a lot to the stories.
One great Naruto Iwa Admiral fanfiction is 'The Stone Admiral's Ascent'. It has an interesting plot where the Iwa Admiral character shows unique jutsu and strategic thinking. It really delves into the character's backstory and how they interact with the Naruto universe's existing elements.
Naruto could meet some young and upcoming Iwa ninja trainees. They might be curious about Naruto and his abilities from Konoha. These trainees could either look up to Naruto or be jealous of his fame, leading to various interactions. Also, there could be some old - timer Iwa ninjas who remember past events involving Konoha and have their own views on Naruto's presence in Iwa.
Another way is that he forms an unexpected alliance within Iwa. There could be a dissident group in Iwa who oppose the capture of Naruto. They might help him escape in exchange for some future favor or because they believe in Naruto's cause. Naruto has a way of inspiring people, even those who are initially his enemies, so this is a plausible scenario.
Maybe he feels ostracized in Konoha. If for some reason the villagers still don't fully accept him despite his heroics, he could be lured by the idea of a fresh start in Iwa.
Well, in fanfiction, if Naruto joins Iwa, he'd likely bring his unique skills and determination. His Rasengan and his never - give - up attitude could shake things up in Iwa. He might also face some initial distrust from the Iwa ninjas as he's from Konoha. But eventually, he could form new bonds and teach them some of Konoha's ways while also learning from Iwa's techniques.