Okay, first thought? Trying to make a humanoid shark character work always feels like a balancing act on a tightrope over shark-infested waters. You can't just slap gills on a guy and call it a day. The stories that do it well focus on the instinctual gap between the shark traits and the human society they're trying to navigate. Is the character constantly fighting the urge to interpret social cues as threats or prey? Does their predatory side make intimacy terrifying for potential partners? That internal friction is the real story, not the cool teeth or gray skin.
I got hooked on a webnovel a while back where the protagonist was exactly that—a reborn assassin in a fantasy world, but his new body was essentially a deep-sea predator given human form. The author didn't just make him 'strong and savage.' His strategic mind from his past life was always at war with this new, primal instinct for overwhelming force. Negotiation felt wrong. Patience felt like weakness. Seeing him try to build a team, to protect people, while his instincts screamed to dominate the hierarchy or eliminate perceived rivals... that's where the human-shark dynamic became compelling. It wasn't about looking monstrous; it was about feeling alien in your own skin.
Too many stories just use the shark aspect as a power-up or a cosmetic quirk. The real balance happens when the non-human traits fundamentally alter how the character experiences the world. Can they ever truly relax around 'softer' species? Does their concept of family become more pack-like, with fierce loyalty but also brutal internal challenges for status? The best ones make you forget the visual after a while and just feel the constant, low-grade tension of being a predator in a world that expects you to be civilized.