Martha Jones
was a doctor, too.
Sort of. If any companion ever understood The Doctor’s implicit need to heal the universe, to help wherever and whenever possible, it was Martha. And Martha thought she could save him from himself. She thought she could be the one to take the pain of losing Rose and smooth it over, help him forget and move on, move on to her. So she stuck by him through thick and thin.
When he forgot who he was and had fears and loves like a human and treated her as a servant or worse, Martha stayed at his side and helped him remember, even when he fell in love with someone else. When he grew so old and withered and physically helpless that he couldn’t even stand properly, when all was lost and friendship seemed a forgotten word, Martha traversed the world though radiation and famine and the constant threat of extermination to inspire the whole of humanity to band together and save the man she loved.
But in the end, it was never enough. Because of the girl with the flower for a name, it would never be enough. There were times when Martha was stronger than The Doctor, when he needed her in order to survive, to save the universe, but in the end, Martha was a doctor, not a flower.
And Doctors never really get quite what they want.