Erwin Green

Doctor Erwin Green was a human who was in London in the 2020s during the Paradox Cloud incident. When the Cloud arrived and started corrupting different locations and items, he ran to hide in his car but the Cloud turned it into a horse and carriage that he became trapped in. He was rescued by the Thirteenth Doctor who with Yasmin Khan collected Paradox Dust that reverted the effects of the Cloud. He revealed that there were Daleks kidnapping humans and imprisoning them, which was a fate he ended up going through himself. Eventually the Doctor and Yaz were able to find the Dalekanium fragments that allowed her to unlock the prison after getting rid of the Daleks and freed him.

Erwin was introduced to the TARDIS as the Doctor used a receive to locate the source of the Cloud. Once she discovered it was on Satellite Five, she bid farewell to Erwin and departed with Yaz to deal with the crisis. (GAME: An Unlikely Heist)