Ng

Ng was originally God's Herald and later a member of Torchwood Three.

Tired of watching God destroy world after world, she hid in Gwen Cooper's body after following the Sorvix through the Rift. The two were eventually split and she remained working for Torchwood using her own identity, discovering who she was as a person without God or Gwen.

Origin
Ng originated on a world in darkness. She had a child, but in-keeping with the traditions of her people did not threat them with much affection. Ng made a deal with a “cosmic force” to gain the ability to jump into other bodies, with her first victim being her child. Each time she moved on to a new body, the force would claim her previous host. (AUDIO: Misty Eyes)

Ng was chosen by God as her Herald. She travelled from world to world spreading the word of God and preparing the inhabitants for her arrival, but tired of all the death as no planet was ready for God's love. (AUDIO: Future Pain) She tried to save the worlds a few times, but nobody ever listened to her. (AUDIO: Thoughts and Prayers)

As Gwen Cooper
When a number of Sorvix fled from Sorva through the Rift, Ng followed them to Cardiff and chose to hide from God in the body of Gwen Cooper as her body was ideal thanks to exposure to Rift energy and she found her interesting. (AUDIO: Future Pain) She took over her body, although she was sometimes able to hear Gwen's voice, and posed as her for a couple of months, raising only slight suspicion from those around her. (AUDIO: Herald of the Dawn)

Hoping to recruit Tyler Steele into Torchwood, Ng saved him from the bombing of the Refugee Crisis Centre, taking him to the Hub. She woke him up after he was knocked unconscious at the candlelight vigil and later comforted him after Jack Harkness refused to give him the job. (AUDIO: Changes Everything) She and St John Colchester went to Madrigal's hen night and ended up on the run with her, avoiding Ro-Jedda's security detail and saving Quenel. Upon returning home, Ng shot and killed Mary Cooper when she became too suspicious of her. (AUDIO: Aliens & Sex & Chips & Gravy)

Ng went to Mary's funeral with Rhys Williams where she let Gwen say goodbye to her mother. Ng's lack of reaction to her mother's death made Rhys concerned about her, but she tried to explain it by saying that she blamed herself. She herself was somewhat worried by Orr's psychic powers (AUDIO: Orr) but later called her in to help investigate the Cardiff Bay Intelligent Hotel and Spa due to her being Sorvan. (AUDIO: Superiority Complex) She had sex with Jack, contracting a parasite from him (AUDIO: Love Rat) and beginning his suspicions about her. (AUDIO: Herald of the Dawn) After she was cured, she slept with Rhys in an attempt to regain his trust, having considered killing him. (AUDIO: Love Rat)

When Tyler investigated Deliverables, he asked Ng to do research on them, but she found herself busy with Anwen and had Orr look instead. Once its nature was known, she shut it down by disrupting the deliverymen. (AUDIO: Zero Hour) She worked to exonerate Andy Davidson after he shot and killed a refugee, eventually confronting Ro-Jedda about it. She and the rest of the team turned against Jack (AUDIO: The Empty Hand) and accepted Yvonne Hartman as their new leader after his link to Red Doors was exposed. (AUDIO: Poker Face)

Ng agreed to look into the murder of Michael Hughes, leading the killer, Serena, to hit her with a car due to paranoia. She managed to struggle to the Hub, retconning a man on the way, and later killed Serena in what looked like a suicide to keep her alien nature secret. (AUDIO: Tagged) Rhys, Mr Colchester and Colin Colchester-Price were increasingly suspicious of her due to her actions in the Escape Room, in which she attempted to sacrifice Mr Colchester. After leaving, she returned to trap Escape and try to get information on God. (AUDIO: Escape Room)

Investigating strange phenomena at a dogging site with Andy, Ng heard Rory Owen say that God was coming. She returned to the Hub and shot an assassin who was trying to kill Tyler and Mr Colchester. When the Rift began opening, she begged Torchwood to close it and Orr was finally able to read her, identifying her as someone other than Gwen. Jack let the Rift split Ng from Gwen and she was rendered unconscious, slowly developing her own form. (AUDIO: Herald of the Dawn)

God and the Reset
Yvonne employed Ng's help in getting information from Ro-Jedda, locking her up in a cell next to Ro-Jedda's and having her pretend to be a prisoner. Whilst in the cell, she ate rats as she needed the protein to stabilise her new form, and was released after telling Yvonne that Ro-Jedda planned to burn the Earth. (AUDIO: Future Pain)

She was subsequently allowed to join Torchwood. (AUDIO: Hostile Environment) Jack compiled a file on her from what little information she gave him, which he sent on to Gwen. (AUDIO: Misty Eyes)

Brent Hayden imagined Ng as an assassin with an English accent. (AUDIO: The Man Who Destroyed Torchwood)

Ng was upset by Jack avoiding her and confided in Orr about it. The two remained in the Hub when a predator shrouded the city in darkness, leaving them blind. The predator made its way into the Hub and Ng ran away from Orr when they began developing its teeth and urges, after which she realised she was in the presence of God. Ng apologised to her and reaffirmed her love for her, but she said nothing. Unbeknownst to her, God sent the predator away. (AUDIO: See No Evil) That night, she stayed awake despite the Night Sun thanks to Yvonne and her caffeine ring, although Yvonne let her go back to sleep as she did not completely trust her. The next morning, she and Jack began to talk. (AUDIO: Night Watch)

Spotting Tyler in the street, Ng agreed to have coffee with him at some point. He later lured her and Mr Colchester with a Weevil report and tagged them with the Oblation app, getting their attention and helping in his bid to find and stop the man behind it. Whilst initially angry, Ng regretted not listening to Tyler sooner. (AUDIO: Hostile Environment)

Ng finally spoke to God after tracking a biotrace to the Evolved technology to an ice cream van. God told her that she was proud of her and that she had switched Torchwood's bodies as a test. Ng refused to pass judgement on her friends and colleagues, pleasing God. (AUDIO: Another Man's Shoes)

Still not completely trusted by Jack, she joined him, Mr Colchester and Norton in stopping the Sorvix power plant from destroyed western Europe. She and Mr Colchester placed detonators around the station and later blasted their way in through the hatch despite Yvonne's orders. Ng found Jack and was in the submersible with him and Mr Colchester when the tsunami hit Cardiff. (AUDIO: Eye of the Storm)

Despite Torchwood's situation after the Disaster Recovery Committee's inquiry, Ng and Mr Colchester continued their work and investigated the death of Jeff Morris, connecting it with ScrapeJane. Although Ng did not initially believe in the monster, she did after Mr Colchester was attacked and was eventually able to destroy it by smashing the stained-glass window that inspired Meredith Pope and telling a story that she believed in. (AUDIO: ScrapeJane)

On Day Zero, Ng and Mr Colchester pretended to be from Water Wales in order to analyse the poisonous mould. They went to the Ritz Tower camp where they witnessed the conflict between the refugees and the DRC's security guards. Ng was worried after Jack was shot and killed and Andy pointed out that he had been dead for much longer than usual. (AUDIO: Day Zero)

Ng took Mr Colchester to Orr, whom they tried to get out of the city to no avail. They were arrested by Andy, who took them to the Hub and told them that he was working for Jack. Ng and Mr Colchester found the Lens and gave it to Yvonne, who used it to direct Orr's powers to destroy the Committee and Erebus. Ng went on the run with Jack, Mr Colchester, Orr and Tyler after Andy informed them that they were fugitives. (AUDIO: Thoughts and Prayers)

Personality
Ng initially lacked any kind of empathy and did not give any consideration to the people whose bodies she stole, even her own child. Her time possessing Gwen however led to her developing a greater sense of humanity, to the point she and Gwen were able to argue the person she had once been was effectively dead. As a result she never intended to steal a body again. (AUDIO: Misty Eyes) Ng was still somewhat manipulative however, such as deliberately withholding information from Orr whilst investigating a cul-de-sac. (AUDIO: Aliens Next Door)

Yvonne described Ng as a hard worker and a good team player, (AUDIO: See No Evil) and believed that she was far more dependable than Jack for handling day-to-day administration. (AUDIO: Another Man's Shoes) Though he was initially reluctant to even talk to her, (AUDIO: See No Evil) Jack eventually came to trust her. (AUDIO: Misty Eyes)

Behind the scenes

 * The character mostly pretends to be Gwen Cooper and, hence, was never named in the Aliens Among Us audios. "Ng" (pronounced "eng") was the way she was presented in the cast lists. In interviews, it was mostly treated as an abbreviation of "not Gwen", and at least once as "new Gwen". The name Ng (with this pronunciation) was used in-universe starting from God Among Us 1.
 * James Goss and Scott Handcock said that the character was pitched by Russell T Davies, who helped to develop Aliens Among Us for Big Finish Productions. It was the only way to include Gwen Cooper in Aliens Among Us due to the unavailability of Eve Myles for most of the recording sessions for the ongoing series. However, Eve recorded a few lines in a single day for the real Gwen, which were used throughout the series, and the final monologue (written by Davies himself) for the final episode, Herald of the Dawn. Though unavailable for the ongoing series, Eve returned to play Gwen for many standalone stories for Big Finish. (BFX: Aliens Among Us 3)
 * According to Goss and Handcock, Alexandria Riley's performance as Gwen "fooled quite a few people", who, upon listening to the first episode of the series, thought that it was Eve Myles playing Gwen. (BFX: Aliens Among Us 3)
 * Russell T Davies suggested that "Not Gwen" should kill Andy Davidson, but Goss and Handcock felt it would be too much, as the character is very much loved by the whole team and the fans, and replaced Andy with Gwen's mother. (BFX: Aliens Among Us 3)