Alaya was a female Silurian warrior from a vast underground city that was disturbed by a Welsh mining facility in the year 2020. She came to the surface and took people hostage. She had a sister, Restac, with whom she shared a hatred of humans and a desire for war to take the planet "back" from humanity.
Alaya came to the surface and took Elliot Northover, Amy Pond and Mo Northover underground as hostages. The Eleventh Doctor sprayed her with a carbon dioxide fire extinguisher and Rory bundled her into the back of a Meals on Wheels van.
She was chained up in the crypt of the church, where she rejected the Doctor's attempts at making peace between the Silurians and humans. When the Doctor and Nasreen Chaudhry left for the Silurian settlement, Alaya said to the remaining group that one of them would kill her and she knew which one, but did not reveal who. (TV: The Hungry Earth)
Alaya stung Tony Mack when she first returned to the surface, but her venom did not kill him as she anticipated. Ambrose demanded that Alaya provide her a cure for her father. Her refusal provoked her into using a taser on Alaya, inadvertently killing her. With her last words Alaya revealed she knew it would be Ambrose who would kill her, as she had the most to lose.
Alaya was sadistic. She enjoyed that Tony Mack was suffering from her venom, though she was surprised that he hadn't succumbed to it. She was strong willed, refusing to give in when Ambrose tortured her and chose to die rather than tell her how to cure her father. (TV: Cold Blood)