Dodo Chaplet

Dorothea "Dodo" Chaplet was an orphan. She may not have left school, or she may have only recently left, and was probably aged about 16 when she met the Doctor. Her grandfather was french, but she was probably a Cockney - although her accent was hard to determine as it could be variable. Before meeting the Doctor, Dodo lived with her great-aunt, but there were indications that this wasn't a particularly happy arrangement as she believed that she woouldn't be missed when she left her home to travel in the TARDIS.

Biography
Dodo's youthful vigour, and excitement in all she saw, reminded the Doctor of Susan, and the pair became close. She took the TARDIS, and Space/Time Travel, in her stride. When Dodo first entered the TARDIS, she believed it was a real Police Box, in 1966. She had entered it wanting to report an accident, in which a small boy had been hurt. The fact that the TARDIS wasn't a Police Box made her intrigued, rather than unbelieving. When Dodo experienced Time Travel, she was equally excited about being on the Ark, as she was to be in the Wild West.

When Dodo, and the travellers, arrived on the Ark she, at first, believed that they are at Whipsnade Zoo. Dodo told the others that she went there as a child, and she displayed some knowledge of nature. Unfortunately, Dodo had a cold, and this virus was accidentally passed on to the Humans and Monoids inhabiting the Ark. As they had no resistance to this virus it became a plague. Dodo, being a caring person, was distraught that she had caused this terrible event.

Dodo's caring nature was probably what made her dislike cheating, unfair, behaviour. Whilst this annoyance could be seen at many times, it was most visible when the travellers met The Celestial Toymaker. It was his games, attitude, and Cyril's cheating which frustrated Dodo.

Whilst travelling with the Doctor, Dodo was lucky enough to have one of her life-long wishes granted. She was keenly interested in the Wild West, and revealed that she had always wanted to meet Wyatt Earp. When the travellers arrived in the American West, the Doctor introduced Dodo as "Miss Dodo Dupont, Wizard of the ivory keys". During their time in this era the Doctor quickly realised that Dodo was "fast becoming a prey to every cliche-ridden convention in the American West." Despite this, and the sad events on the Ark, Dodo's interest, and excitement, were still eveident as the travellers continued on their journey. Dodo was not frightened to investigate on her own, and on the next planet they visited she wandered off while the Doctor and Steven were busy with the Elders and The Savages. She had a look around this planet, and discovered the laboratory of Senta, which was used for the life-force transferance that kept the Elders alive.

This independance may finally have been Dodo's undoing. When the travellers returned to 20th Century Earth, and discovered WOTAN and its War Machines, it was Dodo who WOTAN conditioned to betray the Doctor. On discovering this, the Doctor broke her conditioning, and sent Dodo to the country to recuperate. Dodo never returned, instead she sent her TARDIS key back with Polly, saying that she had decided to stay in London.

The Expanded Universe
The BBC Past Doctor Adventure, "Salvation" reveals that Dodo's mother had died in an accident, after which her father suffered a mental breakdown and had to be hospitalized. Dodo was sent to live with an aunt and befriended an elderly neighbor. However, an alien ship crashed nearby and its pilot killed the neighbor, assuming his physical form. When Dodo learned what happened to her friend, the alien kept her prisoner for some time, until she was able to escape. Seeking help, she spotted a police box (actually the Doctor's TARDIS) on the Common and entered it, becoming the Time Lord's newest companion. The Doctor took his companions to New York in the same time period, where they met and defeated the alien's compatriots.

In "Who Killed Kennedy" Dodo suffers severe and recurrent psychiatric problems as a side affect of being controlled by WOTAN. Shuttled from hospital to hospital, she is eventually sent to the Glasshouse, where she is brutally interrogated by its director about the Doctor. The Glasshouse's director is later revealed to be the Master. Turned out into the street, the homeless Dodo eventually meets and falls in love with journalist James Stevens, who is investigating the activities of UNIT, unaware that he is being used as a pawn in the Master's scheme to destroy UNIT and the Doctor. While Stevens is being interviewed on a live television broadcast, Dodo is murdered by Francis Cleary, a former UNIT soldier, Glasshouse patient, and another of the Master's hypnotically controlled pawns.

Quotes
"Wait a minute, if this isn't a Police Box, what is it? and who are you?"

The Massacre of St Bartholomew's Eve

Steven: "If it isn't allowed Dodo would be first in the queue"

The Savages

"He can bring them to life, but they have wills and minds of their own. I'll never be able to look at a doll or a playing card again with an easy mind.  They really do have a secret life of their own."

The Celestial Toymaker