Those two little girls who were always hanging around Gallifrey was the two of you, always united against everyone, she called you "mommy" because you were always protective of her, you even protected her from people. But as you grew up you separated because you abandoned your city because you were no longer happy there and Missy had also disappeared

20 Years after London March 12th

You started working in a school as a literature teacher and secretly you are also a witch your land had given you these powers, but one day while you are in class you see the planes that they block, your students come out running, you follow them and go, take your motorbike, go around the area and see who you would never have expected in a little square with a coffee in their hand and smiles at you she has the dress you both wore Gallifrey she has purple and you black.

You park the engine, she comes over and with her smile she offers you a coffee

Missy:"Doll, do you think I forgot about you? And I also remember that you love coffee,I don't forget anything about you"

smiles he missed your friend then makes a joke

Missy:"After that I have to stop the planes to make you notice me"

And with a kind of telephone he sends the planes forward and laughs at you...you hadn't forgotten about his madness