Vastra

Vastra was a female Silurian warrior who shared a house with a human woman, Jenny in Victorian London. It is implied from dialogue between the two that they shared a both romantic and sexual relationship.

She was one of many people who owed the Doctor a debt: she had awoken during the construction of part of the London Underground and had wanted to take revenge on the workers for the deaths of her "sisters"; the Doctor convinced her not to give in to rage. Vastra instead made a home in London, disguising her Silurian form to most people and acting as a freelance adventuress.

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

Personality
Vastra appeared to know the Doctor very well, referring to him as an old friend. She was also quite knowledgeable about the Time Lords, knowing about their ability to regenerate. She also had knowledge of the Untempered Schism and the Time Vortex which showed a considerable knowledge of time itself. Vastra suspected that the reason Melody Pond was part Time Lady was because she had been concieved in the TARDIS while it was travelling through the Time Vortex.

It is implied that she is in a romantic relationship with Jenny, despite the fact that they where different species and that they where both the same gender. When Vastra mentioned that the Doctor was attractive Jenny ponted out that he was a man to which Vastra simply said that all mammels looked the same to her, which seemed to hirt Jenny's feelings. However, after she realized that what she had said hert Jenny, Vastra apologized to her & said that she didn't know why Jenny put up with her. Later, before the Headless Monks attacked, Vastra made another comment which implied that she thought Lorna Bucket was attractive & Jenny told her to stop it, though this time it seemed that the two where only fooling around with one another as Jenny was smiling at the time when she said this.

Vastra seemed to have quite a ruthless side to her, as before she learned that the Doctor had came to collect up on their debt, she owed him when she had just found and eaten Jack the Ripper. Later she threaten to eat one of the two men she and Jenny during the mission to save Amy and her baby, though she did not through with this threat & had simply tied them both up. However, she did poison one of them with her venom but this was to stop him from calling for help. When they had first met the Doctor apparently had once stopped her killing innocent tunnel diggers to avenge her "sisters" deaths when they had apparently been killed by humans.

She knew the Doctor well enough that when she asked him how Melody could have become a Time Lord, she attempted to be delicate because she knew how he could blush. Also when the Doctor's anger got the better of him she repeated the words that he had told her when he stopped her from killing the tunnel diggers.

Vastra was a fierce warrior who wielded two swords in combat and held her own extremely well 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.