So let's talk about Ace (Sophie Aldred), the Seventh Doctor's companion (1987-1989) – because I really don't get all the complaints about the current series of BBC's Doctor Who having too much politics. The series always had politics embedded at its core: virtually every Science Fiction, spy or crime TV series created in the UK in the 60's were about fighting fascism as Britain continued to recover from World War II. Doctor Who was no different: the Daleks were inspired by the Nazis from the get-go. Their voices were an exaggerated version of how cartoon Nazis talked in movies. The writers and producers of Doctor Who always wore their antifascism on their sleeves with pride.
The Angry Teen Companion
In 1987, Andrew Cartmel became the script editor of the show and had ambitious plans. He was a card-carrying anti-Thatcherite and wanted a new companion for the Doctor who embodied his more political take on the show. He wanted a feminist companion who didn't need rescuing. Cartmel and the writers he chose were the first generation of writers who were influenced by comics, particularly those written by Alan Moore. This was the period when Swamp Thing, Marvelman were all the rage and Watchmen was just beginning. Cartmel had tried to get Moore to write for the show.
Ace was the nickname of Dorothy, a teenager from the London suburb of Perivale who was more than happy to go around causing chaos with the Doctor. Kids related to her or wanted to be like her. She wore a bomber jacket festooned with CND and probably "Rock Against Racism" badges and spoke like they did. She was the most overt "Social Justice Warrior" out of all the companions and nobody ever complained.
"SJW" With a Baseball Bat
Ace was cool – she beat the crap out of a Dalek with a baseball bat and blew up another with a rocket. She was also very specific – she hated her mother, she burned down a house, she liked to blow things up. Ace was the angriest companion the Doctor ever had, and the most complex. She hated racism and felt ashamed when she shouted a racist word at a friend. Ace fancied soldiers as much as she was suspicious of them.
Ace and the Doctor had a relationship that was affectionate and protective. He treated her like a student or apprentice and she called him "professor" rather than "doctor". She trusted him completely and he secretly delighted in her talent for violence and chaos. He wasn't above manipulating her to beat his enemies and also forcing her to confront her emotional issues, which she resented. The stories more than hinted that the Doctor knew all about her past and had decided to "fix" her.
Cartmel and his writers weaved her backstory deeply into the show. In "Curse of Fenric," she turned out to be a descendent of a bloodline that the Doctor's enemy Fenric controlled over thousands of years. The baby she saves turns out to be her future mother, ensuring Ace's existence. In "Ghost Light," the Doctor takes her back to the late 1880s to the house she burned down a hundred years later. She discovers that she burned it down in 1983 because she sensed the alien psychic energy that lingered in it. Ace's life story became part of the show's story arcs more than any previous companion.
What Cartmel did became a template for the current version of the show. Russell T. Davies, Steven Moffat, Chris Chibnall, and many of the writers were fans of his era. You can find traces of Ace in many of the current show's companions, but none of them are as complex or specific as she was.
Ace After the Show Ended
Ace is the companion whose run never really ended. Cartmel planned to send her to the Time Lord Academy on Gallifrey at the end of her time on the show, but it was cancelled before they could produce her final season.
Ace appeared in dozens of novels and Big Finish audio dramas, but many of the stories were contradictory. Several of them even killed her off, then brought her back again and again. In The Sarah Jane Adventures, Sarah Jane mentions a "Dorothy" who works for a major charity called A Charitable Earth (aka A.C.E.). Davies wanted Ace to appear in The Sarah Jane Adventures, but Elizabeth Sladen (Sarah Jane) passed away and the show had to be shelved.
Aldred said she likes the mystery of not knowing how Ace ended her time with the Doctor. She likes to think that Ace stuck with the Doctor until she grew old and died in front of him, since Ace had no life or relationships on Earth to return to.
Perhaps it's best that way. Ace is still out there, traveling with the Seventh Doctor… gleefully causing chaos.