Bill Potts

Bill Potts was a companion of the Twelfth Doctor.

When she first encountered the Doctor, Bill was working as a canteen assistant at St Luke's University, seemingly destined for an unprivileged life. When free from work, she attended some of the Doctor's lectures at the university. The Doctor saw her unfulfilled potential and invited her for a series of personal tutoring sessions.

Following an encounter with a time-travelling puddle that was piloted by her friend Heather, Bill discovered who the Doctor really was — an alien time-traveller, guarding a secret vault beneath the university campus. The Doctor invited her to join him on a journey through space and time.

Before the Doctor
Bill's mother died when she was young, so she was brought up by a foster mother called Moira. (TV: The Pilot)

At St Luke's University
Later in life, Bill served chips at St Luke's University in Bristol, and — despite not being a student — attended some of the Doctor's lectures. Noticing her potential, he became her personal tutor.

During Christmas, Bill mentioned to the Doctor that she was "supposed to look" like her mother, but, as her mum rarely had any picture taken, Bill didn't really knew if she looked like her. When she went to the flat where she lived with her mother, Moira told her she had found a box with pictures of Bill's mum. On one of the photos, Bill could see the Doctor's reflection.

Over the course of her tutoring, Bill developed a crush on another student, Heather, who showed her a puddle that cast a reversed reflection. Bill asked Heather not to leave without her. As a result, when Heather was taken over by the puddle, she followed Bill home, so as not to leave without her.

Bill went to the Doctor's office, and then he brought her into the TARDIS. He tried to outrun the water creature, and finally travelled to a war zone in the Dalek-Movellan War. Bill realised she was being pursued as Heather had promised not to leave without her. On the Doctor's advice, she released Heather from her promise.

The Doctor took her back to the university, where Bill expressed regret at having turned down Heather's offer, with the Doctor telling her it was unlikely they would ever see each other again. When Bill knowingly looked at the TARDIS, the Doctor realised what she was suggesting and made her stand close to him, intending to wipe her memory of these events, but she convinced him not to. He then agreed to take Bill with him on his travels, acknowledging that they might run into Heather one day. (TV: The Pilot)

Travelling with the Doctor
The Doctor took Bill to visit a human colony in the far future lying to Nardole that he was just transporting the TARDIS back to the office. When the Doctor discovered the Vardy robots had killed the set-up team on the colony, the pair escaped the colony, running from the Vardies and Emojibots, but the Doctor ran back in to attempt to destroy the base for the sake of the coming settlers. The Doctor wanted Bill to stay behind, but Bill followed him, believing that the reason the Doctor kept the TARDIS in the shape of a police box and why he didn't ask for help was because he was the helpline. The Doctor showed her that the Vardies were actually a part of the building and had constructed the colony using themselves. He had Bill give him directions to the main power centre using a map before Bill realised he had memorised the schematics and was keeping her at the map to keep her out of trouble. Bill was horrified to discover the colonists were the last humans in existence after Earth was evacuated.

As soon as the Doctor had wired the ship the city had been built around to blow, Bill emerged with a boy called Praiseworthy. The Doctor realised that the colonists had already arrived in hibernation waiting for the ship to wake them up, and entering the ship woke the colonists. The Doctor stopped the bomb, and the pair deduced that the Vardies had been built to sustain happiness and had come to view grief as a plague.

The Doctor rebooted the Vardies, erasing their memories of the humans, before beginning diplomatic negotiations between the humans and Vardies. He then tried to return to the university just after they left, but when he and Bill exited the TARDIS, they discovered they were outside in winter with an elephant in front of them. (TV: Smile)

On exploring London in 1814, The Doctor and Bill attended the last Frost Fair on the River Thames before noticing strange lights under the ice. Bill witnessed firsthand the death of a little boy when he was sucked under the ice and was horrified and disgusted when the Doctor seemed to care more about retrieving his sonic screwdriver that the boy had stolen. Bill challenged the Doctor demanding to know whether he had ever killed anyone to which he confirmed saying that he did not have the luxury of for outrage as he was 2000 years old. Bill befriended the urchins who had originally stolen from them and chose to cooperate with the Doctor. Their investigation led them to Lord Sutcliffe with the Doctor warning Bill to let him do the talking as it required a diplomatic approach. After Sutcliffe made racist remarks towards Bill, however, the Doctor punched him in the face. Later Bill agreed with the Doctor to set the Monster in the Thames free surprised when it wasn't headline news in the present day. (TV: Thin Ice)

She later helped investigate and stop the Shining Men (PROSE: The Shining Man), visited Kollo-Zarnista Mining Facility 27 above Saturn (PROSE: Diamond Dogs) and, with both the Doctor and Nardole, saved Edinburgh in 1645. (PROSE: Plague City).

Personality
Bill was very smart and very inquisitive. She asked questions that most people didn’t ask and came to conclusions in a different way than other people normally did. She loved science fiction and was open to the idea that the concepts it proposed were real and affected the lives of those around her. When Heather introduced her to a strange puddle, she was open to the idea of alien lizard possession, no matter how preposterous the Twelfth Doctor found it. (TV: The Pilot) She was also rather bold, hating the idea of being spoken to in a sexist manner and having to withhold her opinion due to racial stereotypes of the 19th century. She also learned to understand the need to not dwell on matters that anger her as the Doctor taught her there simply wasn't time to waste on such. (TV: Thin Ice)

Bill had a crush on a girl who attended the Doctor’s lectures, and developed an interest in another young woman, Heather. (TV: The Pilot)

Skills
Bill was extremely bright and quick witted, able to perform well in the Doctors university assessments with his private tuition in the field of science and impressed him enough before had that he saw potential in her. She was also able to deduce complex puzzles with only some prompting from the Doctor, notably that the puddle in the ground was not reflecting as a mirror and that the damaged cement was actually scorch marks of the ships, (TV: The Pilot) and that the lights, which she perceptively noticed, under the ice in the Thames were organic rather than artificial. (TV: Thin Ice)

Appearance
Bill was a young woman with dark skin and afro-textured hair. She didn't like her face because it was "always doing expressions [when she was] trying to be enigmatic". (TV: The Pilot)

Behind the scenes
Bill Potts shares her name with William Hartnell, who was often known as Bill or Billy, while Bill's first love interest shares her name with his wife Heather.