Siren (The Curse of the Black Spot)

The "Siren" was a virtual doctor who accidentally kidnapped pirates from The Fancy.

Abilities
The Siren was capable of taking the image of the injured species; when attempting to treat humans, she looked like a green woman. When interfered with or faced with contaminated material, she would become red and angry.

The Siren's singing acted as an anaesthetic. She used her song to lure individuals to her, although it only affected those from whom she had taken a tissue sample. On touching her, people would be teleported to a sick bay. Her screams were also capable of knocking people around, as happened to Amy. The Siren could also produce fire to sterilise material. (DW: The Curse of the Black Spot)

Personality
The Siren seemed to have limited intelligence, being incapable of communication and being unable to detect the severity of an injury or the reactions to her treatment. The Siren refused to let anyone else help her patients unless they were connected in some way, such as marriage. She then required them to "sign a consent form" by placing a hand in a glowing ring and confirming that they would take responsibility for the patient. (DW: The Curse of the Black Spot)

History
The Siren worked on an unnamed spaceship in another dimension. It accidentally became trapped in the same space as The Fancy, with any reflective surfaces acting as portals to the other dimension. The crew was wiped out by a disease from Earth, leaving her with no patients. With nothing to do, she became aware of The Fancy's presence, and sensed any crew member who was wounded in the slightest way (for example, a small cut). She then took tissue samples of the wounded sailor, leaving a black spot so she could then return and take the sailor to the sick bay to care for. She continued to do so after the Eleventh Doctor, Amy and Rory arrived, despite their attempts to ward her off.

During a storm, she took the Captain's son, Toby Avery. When Rory Williams was knocked off the ship and began to drown, the Doctor exposed a reflective surface so that she could save him. The Doctor, Amy Pond and Captain Avery all allowed themselves to be taken by the Siren to see where they would go. When they found Rory and the crew, Amy showed the Siren her wedding ring, and the Siren gave her consent to care for Rory. Captain Avery knew that his son couldn't be saved, so took over the space ship with his crew, allowing the Siren to care for them. (DW: The Curse of the Black Spot).