Bridget was a Galatean.
During a war between the humans and the Galateans, Bridget went undercover as a nun. She went on a human expedition to a space station where a first expedition of nuns had gone missing. During the expedition she met The Doctor and Amy Pond, who had been brought to the space station by the TARDIS. They found a primitive time engine aboard the spaceship. It was accelerating the flow of time.
This caused a creature to mutate in the TARDIS. It was made up of several life forms absorbed by the TARDIS from the jungle on Planet Basingstoke, which had also grown from the TARDIS.
The Doctor lured the creature into a teleport, where he hoped to reconstitute it into its original parts. The Doctor noticed that Bridget had not aged while everybody else had; this blew her cover.
Bridget activated an army of Galatean plague robots to attack Ivana, Amy, the who had aged many decades and the Doctor. The robots killed Ivana, but she set off explosives near the time engine. This sped the time flow to a dangerous speed. The jungle aged to death and the circuits of all the Galatean robots were scrambled.
The Doctor and Amy survived at the heart of the time storm. The plague robots took them to Bridget and to the mutated creature, which had evolved into Chiyoko. Bridget and the plague robots worshipped Chiyoko as a combination of flesh and machine, the ultimate expression of existence. Chiyoko said "Oh my little tin people, you are so funny!" Before destroying Bridget and the plague robots. (COMIC: Apotheosis)