Caelus X Sunday Novels & Stories

I spent a weirdly long weekend digging through Ao3 for Caelus/Sunday stuff because the potential hit me one morning. The whole CEO/executive assistant dynamic people push sometimes feels off to me, honestly? Caelus isn't submissive, he's more like a chaotic force that Sunday tries, and mostly fails, to contain. I've seen a few where Sunday is the one secretly protecting Caelus from IPC boardroom sharks, which flips the expected power dynamic in a fun way. It adds this layer where Sunday's polished professionalism is a shield he's using for someone else's benefit, not just his own ambition. That clicks better with their hinted backstory.

There's also the 'enemies to reluctant allies to lovers' pipeline that works surprisingly well if you ditch the corporate setting and put them in a high-stakes mission together, maybe even a forced undercover op. The tension comes from conflicting methods—Caelus's instinctive, improv-heavy style grating against Sunday's meticulous, by-the-book planning. You get the verbal sparring, the near-misses where one saves the other despite themselves, and that final moment where the plan goes to hell and they have to rely purely on trust. It's not a new trope, but it fits them like a glove because their canon personalities already suggest that friction.

What I'm less convinced by are the pure coffee-shop AUs. It smooths out all their edges, and their edges are the best part. The appeal is in the clash of worlds, the corporate intrigue, the sense that they're navigating something dangerous together. Taking that away leaves something pleasant but toothless. I'd rather read about them negotiating a hostile takeover while trying to hide their relationship from the press than about them holding hands over latte art.

Never imagined I'd see Caelus and Sunday as a thing, but here we are. It's one of those ships that caught fire on Twitter and TikTok edits before it even had a proper name. The main hub, no question, is Archive of Our Own. AO3's tagging system is built for this exact kind of niche, character-driven pairing. You can filter by the 'Caelus/Sunday' relationship tag and get hundreds of works, ranging from short fluff pieces to elaborate, novel-length AUs. The quality spectrum is wild there, which I kind of love—you get everything from first drafts to prose that could be published.

Wattpad has a presence too, but it feels different. The stories there trend younger, often with more straightforward romantic plots and less focus on the canon-adjacent tension that defines a lot of the AO3 stuff. I've found a few gems, but you have to sift through more self-insert adjacent content. Tumblr is where a lot of the meta and headcanons live, which then fuel the fics on AO3. Honestly, my reading time is limited, so I stick to AO3 and follow my favorite authors on Tumblr for updates. It's a decent ecosystem once you find your people.

I honestly wasn't sure about that pairing at first—Caelus and Sunday feel like they inhabit such different worlds in 'Honkai: Star Rail'. The stories that really got me are the ones that lean into that cosmic/divine versus grounded traveler dynamic. There's a long one called 'Quiet Hour in the Dreamscape' that treats Sunday's whole vibe with such eerie reverence, while Caelus is just this pragmatic, slightly confused anchor. It's less about romance and more about two utterly different forms of existence trying to understand each other. The tension comes from whether their natures are fundamentally incompatible.

Some shorter fics go the enemies-to-allies route, which can be fun if the writing is sharp, but they often fall into cliché. The best avoid making Sunday a mustache-twirling villain; he's too interesting for that. I skip anything where Caelus 'fixes' him—that misses the point entirely. The appeal is the push-pull, the strange beauty of their contrasting aesthetics, not fixing one to suit the other. I've found the most compelling takes on Archive of Our Own by filtering for the 'metaphysical' and 'character study' tags.