Alf is a teenage London girl who used to work on the till in a supermarket, until she was swept away from Earth by a time storm. The Doctor finds her in a distant galaxy ... working on the till in a supermarket. Fed up with her routine job, determined to see the sights of the universe, Alf pours a drink inter her talking till, quits, and joins the Doctor on his adventures in the TARDIS.
Alf is uneducated but sharp, nobody's fool. She has a sense of wonder about their travels through time and space. She is smart and tough but protective of the Doctor. Can also be stroppy and sullen. She appreoaches her cosmic adventuring with a down-to-earth pragmatism and a somewhat offbeat sense of humour.
From this brief description (penned by John Nathan-Turner and Andrew Cartmel) was to emerge the most complex and one of the most popular Companions in the history of the series. For the first and only time, writers were as fascinated with the Companion as with the Doctor, and classic stories like "Curse of Fenric" were the result. Some thought it was about time while others found the altered focus inappropriate. But no one will deny the uniqueness of Ace.
In some ways, Ace was little more than a juvenile delinquent, resistant of authority and impatient with routine. On the other hand, she had a fierce sense of justice and right and wrong, which was perhaps what led to her distrust of authority. And her loyalty to her friends, and particularly to the Doctor, was unquestionable.
She is moodier and less at peace with herself than previous Companions, though perhaps this is a welcome change from the unendingly cheerful Mel. Her lack of self-confidence, though, does not keep her from defending and standing up for herself, successfully and repeatedly. If I had to pick a Companion to guard my back, Ace would be high on the list.
Some of her qualities can be caricatured: her fondness for explosives, her continually calling the Doctor "Professor," her dealings with traditional Doctor Who villains. (After dealing with Daleks with a baseball bat and Cybermen with a bow-and-arrow, I fully expected a season 27 story in which she tackled Sontarans with horseshoes.)
Overall, though, we get to see more inside Ace than we do inside any other Companion. As shown in "Ghostlight," she has a well-defined past, with her hatred of racism from "Remembrance of the Daleks" having its roots in an incident from her childhood. It's never explicitly brought out in the show itself, but we can sense that it's there.
Then there is her relationship with the Doctor. Though strained nearly to the breaking point by the mystery and secretiveness of the Seventh Doctor, not to mention his feigned betrayal at the end of "Curse of Fenric," it must rank among the great Doctor-Companion teams of the past: the Second Doctor and Jamie, the Third Doctor and Jo, the Fourth Doctor and Sarah Jane, the Fifth Doctor and Tegan.... (Well, maybe not that last.) Their banter is delightful, but conceals hidden depths. Ace calls the Doctor "Professor" almost all of the time, but when she's worried, she always reverts to "Doctor." And there's the end of "Ghostlight" (as Sophie Aldred remembers it in her book):
"Any regrets?" asks the Doctor.
"Yes," replies Ace, with a troubled look.
"Yes?"
"I wish I'd blown it up instead," to which, instead of the scripted "That's my girl," Sylvester decides to murmur, with more than a hint of mischief in his twinkling eyes,
"Wicked!"
Back to the TARDIS.