He would probably have a very mixed reaction. On one hand, seeing how fans view his world and his story could be really cool. He might enjoy seeing different versions of himself and his friends. However, if there are inaccuracies or things that go against his values in the fanfiction, he could also be a bit put off. It really depends on the nature of the fanfiction he's reading.
In these fanfics, we get to see our favorite characters from both series in new situations. For example, Naruto might befriend Steven and learn about the power of love and acceptance from him. Or the Gems could be intrigued by Naruto's chakra and want to study it. These crossovers allow for a lot of character development and interesting interactions.
One interesting crossover could be Naruto characters in the world of Steven Universe. For example, Naruto's ability to use chakra could be a unique power in the SU universe. Maybe he could use his Shadow Clone Jutsu to help out in a gem battle. Another could be Steven trying to understand Naruto's ninja way and learning some of his moves to defend Beach City in a new way.
Unique character interactions make a Naruto - Steven Universe fanfic stand out. For example, when Naruto's energetic and head - strong nature meets Steven's kind - hearted and sometimes naive personality, it can create really engaging dialogue and situations.
A 'Naruto meets Steven Universe' fanfiction could start with Naruto accidentally ending up in Steven's world. He'd be shocked by the colorful and strange environment. Steven would be the first to approach him, being the friendly and curious character he is. Naruto would quickly show his combat skills, which would amaze Steven. The Gems might be a bit more cautious at first. But as they learn about Naruto's good intentions, they start to work together. They could share their knowledge of different forms of magic or power. Naruto could learn about gem - based powers and how to use them in combination with his chakra. And they could all go on adventures to protect both their worlds from new threats.
In some fanfics, there could be a situation where Steven visits the Naruto world. He might be really confused at first by all the ninja stuff. But then he could start to use his Gem powers in creative ways to help out. He could heal injured ninjas with his healing spit, and the ninjas would be amazed at this strange power from another world.
In the context of the show's universe, it's a bit of a strange concept. Since fanfiction exists in our real - world fandom and not in the show's world directly. But if we were to imagine a meta - situation where he could access it, I suppose it could be possible. However, it would be a very surreal situation for him.
There's a fanfic where Naruto is transported to the Steven Universe world. In this fic, Naruto is initially confused by the strange new world filled with gems and their society. But as the story progresses, he uses his ninja skills to help the Crystal Gems in their battles. It shows how Naruto's determination and combat skills can be useful in a very different setting.
Perhaps in the fanfiction, there is a threat that only the combined forces of the Naruto universe and the Steven Universe can stop. Naruto and his friends team up with Steven, Garnet, Amethyst, and Pearl. They have to learn to work together, with Naruto's combat skills and the Gems' unique abilities being essential in defeating the common enemy.
A really interesting crossover is when the Gem technology and Naruto's jutsu are combined. For instance, the Gems' ability to teleport could be compared to some space - time ninjutsu. It's fascinating to see how the two different power systems interact.