The Blood Line
Lyn Peterfield was a CIA agent in the 21st century. She was loyal to orders from the top and carried them out, even if they contradicted her previous ones. Such an example is poisoning Jack when her orders were to bring him in America, alive.
Lyn was a cold-blooded killer and CIA agent.
Some time before Miracle Day, Peterfield had a relationship with fellow CIA agent Rex Matheson. However, they got on each other’s nerves, leading to them breaking up, something Rex latter admitted when having an argument with Gwen about her relationship with Jack.
Later, Lyn was sent to help bring Jack Harkness, Gwen Cooper and Matheson back to America as part of a legal rendition. While in-flight and reporting Jack’s conversations to Brian Friedkin (a CIA official), she was ordered by Brian to “remove JH”. At some point learning that Jack was mortal, she tried to kill him by putting arsenic in his cola, but was discovered by Rex and Gwen when Jack started showing symptoms. She was handcuffed while Gwen and Rex tried to save Jack, but when they had almost succeeded she freed herself and tried to stop an antidote (improvised EDTA, ironically using her silver necklace to save the man she poisoned) being given to Jack. Gwen knocked her unconscious when Lyn insulted her ancestry.
When Lyn returned to America, guards pretended to arrest her. Before she could attack Jack, Gwen and Rex again, Rex, having been warned about an ambush, knocked out the guards to free Jack and Gwen. Lyn tried to “restrain” her former lover in hand-to-hand combat, but Rex broke her neck, calling her a “crazy bitch”. She survived due to Miracle Day, and soon after stumbled towards Esther Drummond’s stolen car, her head twisted backwards. Esther, Jack, Gwen and Rex drove away from her and her CIA associates. (Rendition)
She was seen still capable of mobility, despite a presumably paralysing injury, and also conscious. She likely would not have been categorised as category one deceased if she remained functional, but she presumably died when the Blessing was later negated, or in the Modules if she was a category one. (The Blood Line)
BEHIND THE SCENES
Nepalese-born actress Dichen Lachman’s casting in Miracle Day was actually one of the first to be confirmed in media, leading to initial suggestions that she would be a core cast member.