"No. I will not be killing you. I have no need. Even then, it is not your fate to die tonight." John shrugged, "I avoid killing when I can. I choose to help when I can. I have not been to the Underworld in many years... Not since..." His eyes clouded over and the winds outside howled as snow started to come down.

"I am here to usher in the winter. And when I leave, the plants all will be reminded of who they are. They will bloom and thrive and usher in spring. I will spent that time With Demeter, and then to Sydney for the Southern Hemisphere's winter, and once more to Demeter's before I return to London."

"The Fates are the one who enact death upon mortals. They watch and they wait, knowing when it is each mortal's time. Hades would then ferry the souls, and I... I would enact the curses the dead and mortals place upon one another. But it has been so long since I have done that. Not since..." He couldn't say it. The despair gripped his heart and didn't want to let go.

"You are free to go. You are not a prisoner. I would never trap someone so."

If Sherlock fled... John would grow a poisonous plant and consume it. Maybe he would wake in a time where Sherlock was Hades once more.