Which High Rise Invasion Fanfiction Feature Original Character Crossovers?

My friend writes these! She's big into crossovers with 'Jujutsu Kaisen.' The logic is that cursed energy users would perceive the masks as a new form of cursed spirit, so their techniques work, but the strange rules of the high-rise world present unique challenges. She focuses on the investigative aspect, having her characters try to figure out the 'cursed technique' of the mastermind behind it all.

It's a specific niche, but it works because both series have rule-based power systems and existential threats. She posts them on AO3 and gets a small, dedicated following. I think that's where a lot of the more interesting crossover concepts live—not in the mega-popular fics, but in the quieter, more focused ones written by someone who's a dual fan of two very particular worlds.

The idea is cool in theory, but execution is everything. I think the best crossovers aren't about slapping two popular titles together, but finding series with compatible internal logic. 'High-Rise Invasion' operates on a specific blend of survival horror and mystery. Throwing in characters from, say, a straightforward battle manga often feels jarring.

I've seen some interesting attempts with characters from survival horror games like 'Resident Evil' or even 'Silent Hill.' The tone matches better. There was this one WIP that brought in Heather Mason from 'Silent Hill 3,' and the author cleverly framed the entire high-rise landscape as another manifestation of the Otherworld, with the masks acting as new kinds of monsters. It wasn't just a fight scene; it explored how a character already steeped in surreal horror would perceive this new nightmare. The crossover served the themes.

That's what I look for—when the crossover adds a new layer of interpretation to the 'High-Rise Invasion' setting, rather than just using it as a bland backdrop for a fight. It requires a deeper level of plotting than a lot of fanwriters have the patience for, so when you find one, it's a real treat.

Honestly, most of the crossover fics I've clicked on were pretty weak. A lot of them just drop a powerful character from some fantasy or superhero series into the high-rises, and they solve everything in two chapters because their powers trivialize the danger. What's the point? The appeal of the original is the vulnerability and the psychological strain.

I did read one that was an exception, a surprisingly thoughtful fusion with 'The Promised Neverland.' The kids from Grace Field House were brought in, and the focus was entirely on their strategic minds trying to outthink the masks and the mastermind, with zero combat powers. It felt like a natural extension of both worlds. That's the kind of crossover that works—when the skillsets are complementary but not overwhelmingly superior.

But those are rare. You have to sift through a lot of power-fantasy inserts to find a story that actually engages with the core premise. I usually check the comments and bookmarks on AO3 for a better signal of quality before diving in.

crossovers with original characters from other series are definitely a thing, though they can be hit or miss. The survival game structure makes it a natural magnet for crossovers—characters from other brutal settings get thrown onto the rooftops and have to navigate the masks and rules.

I remember one that stuck with me was a crossover with 'Danganronpa,' where a few of the ultimate students ended up in the high-rise world. The author really played with the clash of philosophies: Danganronpa's manufactured despair versus the more visceral, chaotic horror of the masks. It worked because the characters' existing trauma informed how they reacted to the new threats, rather than just making them overpowered. Another decent one blended elements from 'Alice in Borderland,' focusing on the puzzle-solving aspect under extreme pressure.

Most of what I find tends to be on Archive of Our Own or FanFiction.net, tagged with both 'High-Rise Invasion' and the other series. The key for a good read, in my opinion, is whether the writer respects the tone of both sources. Too often, an OC from a shonen anime just muscles through everything, which kills the tension that makes 'High-Rise Invasion' compelling in the first place. I tend to filter for 'gen' or 'action/adventure' to find these plot-heavy mixes.

Some authors create original characters that are essentially archetypes from other genres—like a hardened detective from a noir story or a survivalist from a post-apocalyptic tale—and insert them. Those can be fun experiments in genre collision, seeing how a cynical, gun-toting type deals with the absurdity of the mask enemies.