Place of Origin:
The Return of Doctor Mysterio
Jennifer Fletcher was the daughter of Lucy Fletcher. When she was young, Grant worked as her nanny inbetween saving the world as”the Ghost”. (The Return of Doctor Mysterio)
Eight years after Grant became Jennifer’s stepfather, on a Boxing Day, the Twelfth Doctor returned to the Fletcher family asking Grant for help in finding the three other crystals similar to the one inside Grant. Grant refused to go on the journey unless he could bring Jennifer and Lucy with him.
The first location Jennifer visited with The Doctor and her family was a post-apocalyptic version of New York City. (Ghost Stories)