Lucy was born in Arefu in 2252. Aged 25, she is struck out on her own and headed for the "big city," leaving the small settlement of Arefu and finding her way to Megaton, where she currently resides. Even though Lucy is far from home, she misses her folks and her younger brother, Ian West. She frequently communicates with them via letters she sends there, but as of late they haven't replied, and she fears that either they are in trouble, or the letters simply aren't getting through.
If you kill Evan King, she will refuse to engage in conversation with you.
If you talk to her after visiting Arefu but before finding her brother, you can inform her what happened to her parents, and she will ask you to find him for her. If you complete the Blood Ties quest you no longer have the ability to inform her on what's happened with her family.
She seems to have an attraction to the player character, as after finishing dialogue with her she requests the player see her when visiting Megaton.
During the Blood Ties quest, the player can extort 100 caps from Lucy after discovering the fate of her parents in Arefu. You must have the Scoundrel perk in order for this check to appear.
Lucy's name is a possible reference to the character Lucy Westenra from Bram Stoker's Dracula. They both have connections to vampires, and they were the first victims of a chain of unfortunate events that affect their loved ones.
pcps3xbox360 She will sometimes say "I heard about your little killing spree in Arefu. Get the hell away from me!" after completing Blood Ties, even though no residents of Arefu were harmed. [verified]