(Novelization of Retribution)
Dori was an Umbrella-engineered clone created as part of it Umbrella Prime viral experimentation. She was developed to have the physical maturation of a twelve year old, and lived until the age of three within Umbrella Prime's walls.
Like most clones in Umbrella Prime, Dori was packaged for a testing floor, where she would be killed by the Undead or bio-weapons. JudyTech, a member of staff longing for a daughter, separated her from the others when ready for transport.
After Ada Wong's execution of the control staff, it became clear to Judy that the facility was soon to be destroyed, and Dori went with her to the submarine pens to escape. There, Dori was confronted by Tom Pepper in the kitchens; Judy was able to diffuse the tensions and the three decided to steal the submarine and escape to the outside world, which Dori had yet to see.
Leaving the Russian coast, they arrived at Catalina Island, where the submarine was scuttled and the three joined a group of survivors there.