Because every TARDIS needs a teenager to shriek at historical figures and push random buttons.
Character Overview
Vicki (played by Maureen O’Brien) joined the TARDIS in The Rescue after Susan left. She was an orphan from the 25th century who lost her father, her spaceship, and pretty much all adult supervision. Naturally, the Doctor thought, “Perfect companion material!” and swept her into the TARDIS before she could say, “Actually, I’d like therapy instead.”
Her role was essentially “Susan 2.0,” but with a bit more spunk and fewer awkward grandfather-granddaughter squabbles. Vicki had a wide-eyed enthusiasm for everything, whether it was meeting Richard the Lionheart, wandering onto alien worlds, or pointing out how incredibly old-fashioned Ian and Barbara looked. (To be fair, she had a point: in 25th-century fashion, Ian’s tweed jacket probably counted as prehistoric.)
Of course, being a 1960s Doctor Who companion, Vicki also had to do her share of mandatory screaming. If something moved suddenly, looked vaguely rubbery, or had the audacity to exist, Vicki shrieked like it had just stolen her diary. But to her credit, she wasn’t just a damsel in distress — she was clever, resourceful, and often willing to argue with the Doctor, which was bold considering he had a bad habit of locking people out of the TARDIS when annoyed.
Her most famous moment might be in The Romans, where she gleefully sets fire to Nero’s palace and then treats it like she’d just spilled a drink at a party. Historical disasters? Minor oopsies for Vicki. “Sorry, Rome!”
Eventually, Vicki left in The Myth Makers, when she decided to stay in ancient Troy and marry Troilus. Because what’s more appealing than a man whose city is about to be destroyed by a giant wooden horse? (To be fair, compared to more time in the TARDIS with Daleks and screaming, settling down in the Bronze Age almost sounds sensible.)