Well, it could also be about Naruto straddling the worlds of his past, like the lonely outcast he used to be, and the future where he is a respected ninja. This fanfiction might explore how he copes with the memories and emotions of his past self while trying to fully embrace his new role. It could show his internal struggle as he is pulled between these two very different mental and emotional 'worlds'.
It could be about Naruto existing in two different realms or having to navigate between two contrasting aspects of his world. Maybe it's about his life as a ninja and his inner self which are like two separate worlds.