Born in 2079, just two years after the Great War, Lily lived a simple life in Vault 17- until the Master's army raided the vault. The 75 year old grandmother was dragged outside, where she saw the sun for the first time.

Lily was then dipped in the vats of Forced Evolutionary Virus, emerging as a super mutant. She became one of the Master's elite guards, a nightkin, working sometimes as a spy or an assassin. After the fall of the Cathedral, she and her squad led by Tabitha eventually met with Marcus and formed a community at Black Mountain. When Marcus and Tabitha parted on less than amicable terms, Lily traveled with Marcus to Mount Charleston to begin anew.

Lily now tends to the bighorners in the mutant community of Jacobstown. Like all nightkin, she struggles with her dangerous schizophrenia brought on by excessive Stealth Boy usage, but is aided by Doctor Henry, who considers her to be a primary subject for medical testing in his personal quest to cure the nightkin of their affliction. Unbeknownst to Henry, Lily only takes her medicine in half-doses as it allows her to remember her grandchildren, a recording of whom she carries around on an old holotape.