One possible plotline could be that Naruto discovers a hidden threat to Sandaime before anyone else. Maybe he stumbles upon a secret enemy's plan while on a mission. He then uses his unique skills, like his shadow clones, to outwit the enemy and save Sandaime at the last moment. For example, he could create a diversion with his clones while he sneaks up on the bad guys and disarms them.
Perhaps in the fanfiction, the Sandaime betrays Naruto by revealing his secrets to the wrong people. Like, he tells about Naruto's connection to the Nine - Tails in a way that endangers Naruto. It could be because the Sandaime is trying to protect the village at all costs, even if it means sacrificing Naruto's well - being and trust.
A possible plotline could be that Tayuya is captured by an evil organization, and Naruto goes on a solo mission to save her. He uses his stealth skills to infiltrate the enemy base.
Perhaps Artemis gets lost in a strange dimension that is similar to Naruto's world. Naruto discovers her there and has to protect her from the dangerous creatures in that dimension. He uses his skills and knowledge of the area to lead her to safety. Along the way, they might form an unlikely friendship or even more, depending on the nature of the fanfiction.
One possible plotline could be that Naruto, with his powerful ninja skills, suddenly appears in the world where Rias is in trouble with Riser. He might use his shadow clone jutsu to distract Riser while he rescues Rias. Another could be that Naruto uses his rasengan to break through any barriers or attacks that Riser has set up to keep Rias captive. Maybe Naruto is summoned there by some sort of magic or a wish that Rias unknowingly made, and he then uses his chakra to overpower Riser and save Rias.
One challenge could be that the enemy is too powerful for Naruto to defeat on his own. He might have to quickly level up his skills or find allies to help him. For instance, he might need to convince some of the more reluctant ninja in the village to join him in the fight.
In some fanfictions, Naruto could be facing a powerful enemy that he underestimated. Temari steps in and saves him. This event could then trigger a series of events where Naruto starts to study Temari's fighting style to improve his own skills. At the same time, the two of them could get involved in some political intrigue within the ninja villages, as Temari is from Suna and Naruto is from Konoha. Their relationship could be a key factor in the stability between the two villages.
One possible plotline is that Harry is magically transported to the Naruto world and discovers Naruto is in danger from a new, powerful enemy. Harry then uses his magic to fight alongside Naruto and his friends, saving Naruto in the process.
The plot could also involve a time - related crisis. Maybe something is threatening the timeline, and the only way to fix it is for future Naruto to raise his younger self in a certain way. So, future Naruto has to make sure that the younger Naruto grows up to be strong enough to face this threat while also maintaining the integrity of the timeline.
In a 'Naruto son of Sandaime' fanfiction, the story could center around the relationship between Naruto and the other clans in the village. As the son of the Sandaime, they might view him differently. Some clans could try to befriend him for political reasons, while others might be jealous or suspicious. Naruto would have to navigate these complex relationships while also dealing with his own growth as a ninja and his desire to be recognized for his own merits, not just because of his father.
One possible plotline could be that Naruto somehow ends up in Akeno's world. They meet and at first Akeno is a bit shy around Naruto. Naruto, with his positive attitude, gradually befriends her. They could go on adventures together, like facing some common enemies in Akeno's realm. Naruto's ninja skills would be very useful in such situations.