Elizabeth is the great granddaughter of Benny Lafitte.
Elizabeth is the manager at a gumbo shack in which Benny, whom she knows as "Roy," sought out employment, and in his time has developed a close relationship with her. Dean arrives Carencro, Louisiana, to investigate vampire killings of which Benny is the perpetrator, according to Martin Creaser. Dean tracks down Benny and begs an explanation, but is prepared to dispatch his good friend if he has in fact been killing. Benny convinces him that he's kept his nose clean, mostly because being near his family is keeping him honest--Elizabeth is his great granddaughter. She doesn't know, and he wants to keep it that way. He's not killing, but he knows who is, and is going to take care of it himself.
After Benny kills rogue vampire Desmond, he leaves town at Dean's urging. Meanwhile, Martin goes to the gumbo shack and sets Elizabeth up as bait to get Benny. Benny returns to find Martin holding a knife to Liz's throat. Martin reveals to a terrified and confused Elizabeth that "Roy" is her great-grandfather and inflicts a small cut on her neck to bring out Benny's bloodlust. Not willing to harm her, Benny appears to succumb to Martin's blade. Elizabeth screams in horror.
On the road, Dean receives a distress call from Elizabeth begging him to come back to the shack. He arrives to find Liz bloody and traumatized on the front steps. Inside, he finds that Benny killed Martin to protect himself and Elizabeth.
In Torn and Frayed, Dean tells Benny that he knows what really happened with Martin since Elizabeth told him.