The sheer variation I've seen just from browsing 'Toothless' tags on Tumblr alone tells me there isn't one mold. A lot of writers default to the classic 'manipulative seductress' archetype—this icy, calculated creature who uses allure as a weapon and views humans as playthings or prey. It’s a solid foundation, but it can get repetitive fast.
What grabs my attention more are the subversions. I adore stories where the siren’s song isn't about malicious control but an involuntary, almost painful empathy. They don't lure sailors to drown them; they’re overwhelmed by the loneliness and longing in a human heart from miles away, and their song is an instinctive, mournful echo. Their power is a curse of connection, not a tool. Makes for a fantastic slow-burn where a sailor might be the first person to see past the myth to the being trapped inside it.
Then you’ve got the ‘domesticated’ siren trying to blend in, constantly muffling their own nature, which is pure comedy or angst fuel. The real trend I’m noticing lately leans into the feral and ancient—not pretty mermaids, but something older and more unsettling, whose beauty is just one facet of a deeply alien consciousness.