Vastra

Vastra was a female Silurian warrior who shared a house at 13 Paternoster Row with a human woman, Jenny, in Victorian London. They shared an intimate relationship.

She was one of many people who owed the Eleventh Doctor a debt; she had awoken during the construction of part of the London Underground and had wanted to take revenge on innocent tunnel workers for the deaths of her "sisters". After Vastra had slaughtered at least five commuters, the Doctor convinced her not to give in to rage. She made a home in London, at first making a living as the main act in Henry Gordon Jago's "Monstre Gathering" and then as a masked bank robber

After finding lodgings above a gin palace in Cheapside, she came across Jenny, a match girl who was being molested by a Chinese gang. She saved Jenny from the Tongs and subsequently began a relationship with her. (REF: The Brilliant Book 2012)

After tracking down and eating Jack the Ripper (a task which she had conducted in conjunction with Scotland Yard), she was summoned by the Doctor to help in the mission to rescue Amy Pond and her baby from Demon's Run. She and Jenny arrived at Demons Run along with an army of Silurian soldiers. They both survived the battle with the Headless monks, showing skilled swordsmanship in a battle. It was implied she had known the Doctor for some time as she referred to him as an old friend. The Doctor had also told her about Time Lords as she referred to regeneration, the Untempered Schism and the time vortex. (DW: A Good Man Goes to War)

Following their return to their own time, Vastra and Jenny were added to the Papal Mainframe "most wanted" list. (REF: The Brilliant Book 2012)

Personality
Although Vastra enjoyed eating humans when she had cause to do so, she also had a romantic relationship with Jenny. Vastra was able to control her darker urges as she spared the lives of two men when she and Jenny were helping the Doctor despite commenting that she was hungry. She poisoned one of them with her venom, but this was only to stop him from calling for help. When her sisters died in hibernation, Vastra was enraged, but with the Doctor's help she was able to control her anger and did not seek revenge on the humans who awakened her.

Vastra was a fierce warrior who wielded two swords in combat. She held her own against a group of Headless monks, surviving without any apparent injury. She was also very loyal and protective, ordering her allies to protect Melody Pond at all costs. Vastra was an old friend of the Doctor and seemed to know him quite well.

Other information

 * While she shared some of the prejudices that many members of the Silurian race have against humans, stating that all "Mammals" looked alike and threatening to eat one, she was much more tolerant and accepting of humans than many of her species, apologising for her remarks about humans to Jenny and showing concern for the safety of Melody.
 * At one point, Vastra visited Egypt and was mistaken for a god. At another stage, she and Jenny battled a CyberNeomorph. (REF: The Brilliant Book 2012)

Behind the scenes

 * Since their appearance, Vastra and Jenny have become quite popular among the fandom, with fans wishing for a spin-off series to be made based on their adventures. Steven Moffat addressed this, saying that he considered making a spin-off when he created the two characters, but wouldn't have the time, though he said he would like to revisit them.