One possibility could be that Naruto discovers a new and ancient jutsu that allows him to summon Slifer the Sky Dragon. This could completely change the power dynamics in the Naruto universe. Maybe he uses it to defend Konoha against a powerful new enemy, and the dragon's abilities like its powerful lightning attacks give Naruto an edge in battle.
Some fanfictions also revolve around the idea of Slifer being summoned in modern times outside of the normal game rules. This could lead to all sorts of interesting situations, like how the modern world would react to such a powerful and ancient entity. And then there are those that explore the idea of Slifer evolving or changing its form, which adds an element of mystery and excitement to the story.
The reaction would be mixed. His friends like Sakura and Kakashi might be initially shocked but then support him as they trust Naruto. However, some of the more traditional ninja clans might see it as a threat to the balance of power. They could try to either control Naruto or get rid of the dragon.
You can try fanfiction websites like FanFiction.net or Archive of Our Own. They usually have a large collection of fanfictions related to various topics, including Slifer the Sky Dragon.
One idea could be a young Naruto discovers an ancient scroll that allows him to summon dragons instead of toads. He then has to train with these dragons to master new jutsus. Another could be that the dragon summons are from a different dimension and bring with them a new type of chakra that Naruto has to learn to control.
A likely main summon could be Gamabunta. He's big, powerful, and has a long - standing relationship with Naruto. He could teach Naruto some really advanced water - based jutsu.
The Snakes, especially those related to Orochimaru's summons, are often used in fanfiction. They can bring an element of mystery and danger. Some fanfictions might explore the idea of a redeemed snake summon that helps Naruto in his quests, or a more powerful, ancient snake that was hidden away until now.
Yes, in many Naruto fanfictions, Naruto has summons. Fanfiction writers often explore different types of summons for Naruto that might not be in the original story. For example, he could have unique or powerful creatures as his summons, which adds an exciting new dimension to the story.
I'm not sure which novel you're referring to because you didn't provide a specific name or description. But according to what I know, Naruto, Dragon Ball, and Reaper are all famous anime works that contain many powerful characters and abilities. If you can provide more information, I will be more than happy to provide you with a more accurate answer.
Obviously Naruto is likely to be one of the main characters. He might be the one who has the most interaction with the sky dragons. There could also be a new character created specifically for this fanfiction who has a special connection to the sky dragons.