One possible antagonist could be a rogue ninja from another village. They might target Tenten for her unique weapon - handling skills, thinking they can use her to create powerful weapons for themselves. Naruto would then have to face this ninja to save Tenten.
Well, in this fanfiction, Naruto might save Tenten from a powerful enemy. Maybe she's captured during a mission and Naruto uses his shadow clones and Rasengan to rescue her.
Well, in fanfictions there could be various ways. He might use his Rasengan to create an opening in Gi Sensei's defenses and then rush in to save Tenten. Another possibility is that Naruto uses his speed and agility, enhanced by the Nine - Tails' chakra perhaps, to dodge Gi Sensei's attacks and reach Tenten before she gets hurt.
I'm not sure who Gi is in this fanfiction as I haven't read it. But it could be an original character created by the author of the fanfiction, perhaps a villain who poses a threat to Tenten.
Well, without reading the 'naruto saves tenten from gi' fanfiction, we can only speculate. It could start with Tenten getting into a situation where she is captured by Gi. Naruto then gets wind of it and sets out on a mission to save her. Along the way, he might face challenges like other enemies or traps set by Gi. When he finally reaches Tenten, he might have an epic battle with Gi. And after rescuing Tenten, they might share a moment of gratitude and friendship, strengthening their bond within the Naruto universe.
Well, it could be that Naruto stumbles upon a strange situation in the fanfiction world where Tenten is in some sort of distress related to the gay fanfiction plot. Maybe he uses his ninja skills to disrupt the flow of the fanfiction and rescue her. He could use his shadow clone jutsu to create distractions and then whisk Tenten away to safety.
In the context of fanfiction, Gi Sensei might be after Tenten because she has some unique knowledge about an ancient ninja art. He believes that by capturing her, he can extract that knowledge for his own gain. Or maybe he was hired by someone who has a vendetta against Tenten. There could also be a misunderstanding where Gi Sensei thinks Tenten has wronged him in some way, even though she hasn't, and that's why he's targeting her.
It could be that Might Guy is under some sort of mind - control. So, without his normal self - control, he attacks Tenten, making it necessary for Naruto to save her.
It could be a group of outcast ninjas who have a grudge against the Hidden Leaf Village. They target Tenten as she is an easy target for them to vent their anger on. They might be jealous of the Hidden Leaf's prosperity and think by abusing Tenten, they can send a message to the village.