Sally and the Strange Castle
Here is an illustration I made recently.
Sally swam a thousand miles to the icy arctic North. She met polar bears and penguins and even a whale. She spent months and months swimming in the icy waters until her skin and blood and organs froze and she was a frozen woman who would surely melt if she left the arctic North. So instead she built a tower in the snow. The tower was made of rocks she collected form the ocean ground. It was her castle, her fortress, her sacred place of peace.
Sally befriended other frozen people, but frozen people are mostly loners living lives of ice because they don't want the warmth of companionship. Sometimes a frozen person would stay with her for a couple of days or a couple of months, but mostly her frozen friendships were short lived. Her longest friendships were with the animals. She befriended walruses and penguins and polar bears and read them stories and sometimes taught them dance moves people made up in the civilizations of the south.
When Sally wasn't reading or befriending animals, she was mostly swimming. Sometimes she swam so deep down she would come across submarines manned by humans who would see her and gawk with astonishment. They would go home and tell stories of the frozen mermaid but nobody ever believed them.