Helen

“The main courtyard was filled with warriors - mermen with fish tails from the waist down and human bodies from the waist up, except their skin was blue, which I'd never known before.Some were tending the wounded. Some were sharpening spears and swords. One passed us, swimming in a hurry. His eyes were bright green, like that stuff they put in glo-sticks, and his teeth were shark teeth. They don't show you stuff like that in "The Little Mermaid.”
― Rick Riordan, The Last Olympian