Sarah believes the goblin king is real and Y/n, not so much. Y/n is unfortunately unwell. She is suffering from a terminal illness involving lung cancer. No one knows about it except her parents doctors and herself, or so she thinks. After offering to help with babysitting, Sarah has a mental breakdown of some sorts. Trying to calm down her younger brother she fails. but somehow Y/n banishes her brother to the Goblin king. And so the quest to find Sarah's brother begins. Also like you can't grow old in the labyrinth, cause like The goblin king is 300 years old so yeah