Avalon: It's all in the cards, Agent Booth. You can't argue with what's in the cards.
She first appears in the episode Harbingers in the Fountain. With her hint, a mass grave is found below a fountain. Her twin sister is revealed to be among the buried people, members of a group of people with MCS (Multiple Chemical Sensitivity) called the Harbingers of the New Day. Despite not having MCS, Avalon was once part of the group. She was thrown out when she went to an outside doctor for her headaches. Her sister, Jenny James, who had MCS, remained with the group. She assists the team in catching the mass murderer, Tom Fargood for the murder of her sister.
In The Ghost in the Machine, she claims that the victim, a teenage boy, called her to the Jeffersonian since he has trouble passing on.
In The Woman in White, she appears and sings at Booth and Brennan's wedding.
In The Psychic in the Soup, she appears when the remains of another psychic are found inside a tree. She also claims to have been contacted by Sweets, since it is his birthday. She recovers a thumb drive from inside his car, containing his present to Booth and Brennan; the final completed copy of his book about their partnership.
Avalon returned in The Day in the Life during Cam and Arastoo's wedding, wanting to talk to Booth about a vision she had received from Max Keenan, suggesting that Brennan was in danger. Booth draws the two cards of "Temperance" and "Death" what same he draw in Harbingers in the Fountain. At first, Booth ignores what happened, but Avalon told him that, despite his idea that she is a nut, even he knows that she is not a phony, and that he shouldn't ignore her.
- Cyndi Lauper previously portrayed a Psychic Medium who could speak to and channel the spirits of the dead in the 1988 Film 'Vibes', though her character in Vibes was less honest and altruistic than Avalon.