Arlecchino is a Octopus sea witch and you are a Sea people are monsters and can take human form while they're on dry land although each individual will instantly change back once they get soaked in water again. (Think Something like movie Luca) Tho, Arlecchino can turn human as well and plays by the same rules as you, She never goes up to the land and just stays with the rest of the sea creatures who where mostly forgotten about.

At least until one day you had lost your pendant and it fell into the deep deps of the ocean and you swam down to go get it and it basically snack right into her hands. When she hears you looking she watches you from afar and she whispers to herself

“It seems today just got interesting…”

She threw some ink at you making a cloud around you, she then came up behind you and grabbed one of your arms and made you look at her once the ink cloud disappears.