Man, this pairing always seemed like such a long shot to me until I started digging around for fics that actually make it work. It's not the most popular ship by a mile, which honestly means the stories that do exist are usually written by people with a very specific vision, not just hopping on a bandwagon. The best ones tend to be set post-canon, after 'Naruto' ends, because you have to age Shion up and let Naruto's character mature past the hyperactive genin phase. I keep coming back to 'Oracle's Gambit' on FanFiction.Net—it's a slow political thriller where Naruto, as Hokage, has to negotiate with the Land of Demons for an alliance, and Shion is navigating her own court's intrigue. The tension isn't just romantic; it's built on mutual respect and the weight of their positions, which feels way more authentic than just throwing them together.
Another one I'd recommend is 'Of Prophecies and Foxfires,' though it's been a while since it updated. It's more of a crossover-esque adventure where Naruto gets stranded near the Land of Demons during a mission and ends up as an unofficial bodyguard for Shion. The author really nails Shion's aloof, priestess-like demeanor without making her cold, and Naruto's persistence chips away at that in a believable way. It's less about grand romance declarations and more about two isolated people—one by duty, one by circumstance—finding an unexpected understanding. The downside is that a lot of the great Shion/Naruto fics are either one-shots or abandoned, so you learn to appreciate the completed gems even if they're shorter.
I'd also say don't sleep on Archive of Our Own for this pairing; use the tag filters carefully. Sometimes the best treatments are in larger ensemble fics or stories focused on other characters where Shion and Naruto are a developed side pairing. The quality over sheer quantity rule is super true here. You sort of have to sift through the 'Naruto saves Shion from a demon again' repetitive plots, but when you find one that explores Shion's prophecy powers interacting with Naruto's fate, or how her view of predestination clashes with his 'never give up' ethos, it's pretty satisfying. Just brace yourself for a smaller pool to choose from compared to the big ships.