I mean, the 'best' is totally subjective, right? My personal holy grail is this older, nearly abandoned WIP on AO3 called 'Rainmaker.' It’s a post-game canon-divergence where Neku stays in the UG and slowly, painfully learns to co-revive Shibuya with Joshua. The prose is dense and almost overwritten at times, but the sheer tension in their conversations—all that unspoken history and mutual manipulation slowly thawing into something like respect, and then into something terrifyingly close to affection—it’s brutal and beautiful. I’ve re-read the last posted chapter maybe a dozen times, just living in that ambiguous, heart-wrenching silence between them.
For something completely different and actually finished, 'Frequency Shift' is a solid bet. It’s a modern AU with Neku as a tinnitus-suffering music producer and Joshua as a mysteriously wealthy patron with too-perfect hearing. It sounds cracky, but the author really gets their dynamic: Joshua’s chaotic, almost cruel curation of Neku’s talent, pushing him to emotional extremes to create, and Neku’s stubborn resistance that inevitably turns into collaboration. The romance is a slow, grating burn, exactly as it should be for them. Honestly, most coffee-shop or college AUs for this pair feel off, but this one works because the core power imbalance and artistic intimacy translate so well.
I’d avoid anything that makes Joshua too soft or Neku too clueless. The magic is in their sharp edges fitting together weirdly, not being sanded off.