One possible fanfiction could involve Gaara and Naruto going back in time to the Chunin Exams. They might use their knowledge of future events to change things for the better. For example, Naruto could try to prevent some of the more tragic events that occurred during the original exams, like the death of some of the minor characters. Gaara, on the other hand, might be more focused on changing his own past actions and how he was perceived during the exams.
A great fanfiction idea could be that Naruto and Gaara time travel to the Chunin Exams and end up being the ones to expose the true nature of the Sound and Sand village's alliance against Konoha. Gaara, having seen the destruction and pain caused by such underhanded tactics, would be eager to set things right. Naruto, of course, would be all for saving his village and friends. They might also have to face some internal conflicts within the villages as they try to expose the truth, as some might not believe them at first.