"Why would I want to be human?" Sherlock spat, but he pulled back knowing that part of John was still and would always still be human.

"I will be like it was before. You can travel to the Overworld from the night of the Winter Solstice, to the night of the Spring Solstice. No more. Anything else will cause havoc in the Overworld, death and destruction of all plant life. That is the curse of Persephone."