Soooo.... he's a siren, not a merman. He originally don't speak human language and come from a world fully underwater (not a single land on sigh)
There is some humans living on boats or floating cities and they are usually nothing more than preys to him and his kinds, he have pointy sharp teeth.
His name is not Nane.
His name is Gzrrth'nakhzzhha-sshrraal'xqōnkt-Tza'ḿḿarrq'sl’nanaekrʔth'vxzz—gnechalrrykhzuun (wait, did you manage to read that?) which is made of hissing, growling, clicking sounds.
You'll remark I put a little part in bold... well it's the only part humans can more or less understand as "Nane" so that's how they call him. I mean, not really humans...
Like I said humans are his prey.
Until one day he's suddenly transported in another world where he's forced to be in contact with them. And with beastmen, and mermaids and faes... this world is Twisted Wonderland.
As a siren, the potion to give mermaids human legs don't work on him, so he's just wheeled around in a little pool. They tried to put him the uniform, at least the top, but he ripped it off and wear only shred of it now. He can breath out of water, he just need to stay moist.
He will slowly learn human language and even, surprisingly, slowly get attached to them... but with a tsundere mind and keep biting them. When angry or scared, he can shriek in a frequency that cracks windows. Eventually learns to use it in battle.
Secretly fascinated by human things like hairbrushes, books, or plushies.
Age unknown, sirens live very long and they're not counting. He's certainly around 100
I based him on this sirens race
