The Doctor is Trans.
Doctor Who is left wing- see the Evil Capitalists in Space plots, such as Oxygen, where air is discharged to preserve market value. But the first trans character was a satire. Lady Cassadra, the malevolent trampoline, had had hundreds of operations, the latest bleaching her blood so that veins did not show. I get it- lots of people find vaginoplasty or FFS repellent to imagine- but it is a vicious swipe at trans from a gay writer. And I might not have realised, until she said “When I was a little boy”.
Missy, however, explains The Master perfectly. He is trans, pre-transition. He wants to destroy things, he is so angry; he wants to control, in a horrid caricature of Manliness, and eventually he goes mad.
Then he transitions, and she is playful. This is the first time the character has shown joy. She dresses like a tranny with poor dress sense. She dresses in a particular style- cameo brooches were fashionable in 1996, wasn’t it? Those skirt suits with maxi skirts, the pussy-bows, the high collars, all very trans. I have worn suits like that. I still have a skirt like that. I like it, I wear it occasionally.
She is lonely, and wants her friend back. She despises human beings, thinking less of killing us than we would of killing a spider, but wants to be friends with the Doctor. Her first plan was to give him a present, an army of cybermen so he could “do good” all over the galaxy.
The broken, insane character transitions, and is still broken and insane, but slightly less violent. She might even become sane.
And now The Doctor will be female. This is a mature transition, the gentle, peaceful Doctor who will sacrifice self over and over again for friends, becomes a woman. She is beautiful and retains the deep sanity of the character. This is a transition for now, not the poor persecuted broken trans of the past but a trans person never broken by the world, fulfilled by transition, effortlessly herself.
Her first line when she sees her reflection is “Oh Brilliant!”