Madame Vastra is, in her own words, ‘a lizard woman from the dawn of time’ who currently lives in Victorian London where she’s married to Jenny Flint. She has shown immense compassion to the Doctor and his friends but don’t get on the wrong side of this Silurian… She’s been known to eat her enemies!
Vastra understands the Doctor better than most and clearly feels an affinity with him. After his regeneration on Trenzalore, she told Clara, ‘I wear a veil as he wore a face. For the same reason… The oldest reason there is for anything: To be accepted.’ And she was loyal enough to be stung by Clara’s problem accepting the Time Lord’s older appearance. ‘He looked like your dashing, young gentleman friend… But he is the Doctor. He has walked this universe for centuries untold! He has seen stars fall to dust!’
Clara! Give him hell! He’ll always need it…Vastra
The Doctor first found Vastra in the London Underground system where, as she put it, she was ‘attempting to avenge my sisters on perfectly innocent tunnel-diggers’. He intervened, teaching her that ‘anger is always the shortest distance to a mistake’. It was a piece of wisdom she would remind him of much later, on the eve of the battle of Demons Run.
By that point they had already developed a sound friendship. She felt comfortable teasing the Doctor and gently challenging him when she sensed his judgement was impaired by emotion. She was familiar with the concept of regeneration, knew about his people and even recognised their cellular make-up, indicating that she’d learnt much from the man she called ‘old friend’.
Back in Victorian London, her alliance with Jenny and Strax became known as the Paternoster Gang, with the trio sometimes joined a fourth member - the Doctor himself. She was by his side as he battled the Great Intelligence in 1892 and the following year she helped him defeat Mrs Gillyflower and Mr Sweet.
It’s clear that the Doctor has enormous faith in Vastra. When he needed a team to help him rescue Amy from Kovarian, he called on this remarkable Silurian who became one of his elite band at the heart of the dangerous operation. Later, when he became something of a recluse on Earth, Vastra was one of the few figures he kept in touch with, despite his apparent annoyance at her efforts to coax him into action again.
Perhaps it wasn’t coincidence that when the Twelfth Doctor needed help, immediately after his regeneration, out of all of the infinity of time and space where he could have landed, the TARDIS ended up within miles of Madame Vastra… And her reaction when she saw he had regenerated into what appeared to be a completely new man? A nonchalant, ‘Well then… Here we go again!’