Ng

"Ng", previously known only as the Herald, was 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.

Time as the Herald
Ng was created by God and was known 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)

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 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's arrival
Ng was imprisoned in the Hub (AUDIO: Future Pain) before being released by Yvonne Hartman to work for Torchwood. Jack refused to associate with her because of Gwen's departure being her fault. (AUDIO: See No Evil, Night Watch) She was almost attacked by the predator but God sent it away. (AUDIO: See No Evil)

Ng was initially somewhat dismissive of Tyler's predicament until he tagged her and Colchester with the Oblation app. (AUDIO: Hostile Environment) Ng met God in an ice cream van where God told her that she had been the one to switch Torchwood's bodies and left her with the Evolved technology. (AUDIO: Another Man's Shoes)

Despite Torchwood's situation after the Disaster Recovery Committee's inquiry, Ng and Colchester continued their work and investigated and defeated ScrapeJane. (AUDIO: ScrapeJane)

Ng and Colchester pretended to be from Water Wales in order to test the reservoir during the water crisis. (AUDIO: Day Zero) She fled Cardiff with the rest of Torchwood after the Committee was thwarted by Yvonne and Orr. (AUDIO: Thoughts and Prayers)

Behind the scenes

 * The character mostly pretends to be Gwen Cooper and, hence, is never named in the Aliens Among Us audios. "Ng" (pronounced "eng") is 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 (with this pronunciation) is 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, which were used throughout the series, and the final monologue (written by Davies himself) for the final episode. While 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)