(DeCandido's novelizations of Anderson's Films)
Dahlia Julia Mancini was a survivor of the global T-virus pandemic which ravaged the Earth in 2002. She disliked her name, preferring friends to call her "D.J.". After being rescued from a Kmart store, she used that as her new name.
At some point after the initial catastrophe, Kmart was discovered by Claire Redfield's convoy and has since traveled with them before encountering Alice.