Idris

Idris was a woman who was used as a host for The Doctor's TARDIS.

Biography
She found herself on House when a temporal rift caused her to be transported there. On the asteroid, she lived with Uncle, Auntie and Nephew. She was later drained of her mind and soul in preparation for the arrival of a Time Lord, the Doctor. When he, along with Amy Pond and Rory Williams, arrived on the planet, they were spotted by Idris, who started kissing (later biting) the Doctor, calling him 'her thief', and spoke madly. Uncle and Auntie said she was mad, and Nephew took her to get some rest. Idris asked if there was an 'off switch' and instantly fell asleep, before being carried away by Nephew. The Doctor later found Idris, who told him that she housed the TARDIS' soul. They talked (and flirted) until their non-linear flow of conversation began to make sense and the Doctor let her out of her 'cage'. They met Auntie and Uncle, who dropped dead, unable to live without House's presence, and they realised Idris had little time to live. Eventually they agreed to rebuild a TARDIS console from all the junk, while they bond. Idris infused the mechanical bits with a part of her inherent energy (matrix/soul) to allow them to follow House. During this time, Idris revealed that she allowed the Doctor to steal her from the Time Lords. She wanted to escape from Gallifrey and see the universe, so she "stole" the only Time Lord mad enough to travel with her.

House had raised the shields of the TARDIS. They needed to be lowered so the Doctor and Idris could enter. The Doctor has Idris sent a telepathic message to 'the pretty one' with details on how to get to a backup control-room; having different opinions than the Doctor, Idris sent the message to Rory instead of Amy. They arrived outside a door which had opened upon Amy mentally visualising four words Idris sent Rory. They entered one of the old control rooms and bring the shields down, closely followed by Nephew (revealed to be House's servant). The new console landed on Nephew, blasting him into atoms. The Doctor quickly introduced Amy and Rory to Idris and engaged in conversation with House, offering help to him. He suggested that he delete 30% of the rooms for power. House agreed - and deleted the room the group are in.

The group were suddenly standing in the main control room, as all living things in deleted rooms were transported there. House didn't care, though, since the TARDIS had now reached the normal universe. The Doctor pretended to congratulate House for defeating them, while Idris, about to die, whispered something into Rory's ear. The Doctor revealed that House's plan was to trap the matrix in a mortal body then allow it to die and be released a long way from the TARDIS. Instead, the matrix was released inside the control room and merged back with the TARDIS. It proceeded to purge House from the TARDIS. The matrix had one last conversation with the Doctor from Idris' body, saying the word she never got to say to him: "Hello."

As the Doctor started putting a firewall around the matrix, Rory informed him that before she died, Idris told him 'the only water in the forest is the river', and that they would need to know that some day. (DW: The Doctor's Wife)