While she is half-demon and half-human like her sister Callie, it is not clear if she is also a succubus as she and Callie seem to be very different in their demonic aspects. In the end Lillith turns into a powerful colossal demon that resembles Twayne Boneraper's mother Violet Boneraper.
Lillith is born only one day after Aldermach Maggotbone and Rosie had sex on a pool table during a counseling session with Mark Lilly. This quick birth is contributed by the hormone injections her mother has been taking, which also causes Lillith to age at an accelerated rate of one year per day.
Since Callie is unwilling to marry Twayne Boneraper, Aldermach decides to replace her with Lillith to fulfill his blood pact with the Bonerapers.
Lillith appears to be more evil than Callie, evidenced in her constant use of demonic powers to hurt people. She even knocks her mother off the balcony, seriously injuring her. As a result, Mark and Callie raise Lillith as their own.
Callie feels guilty because Lillith is taking her place to marry Twayne. She tells Lillith it is okay to get out of the marriage, but Lillith says she's going to do the exact opposite and marry Twayne anyway.
On her wedding ceremony, Lillith tells Mark that she plans to kill both Twayne and Callie and marry Mark instead. Then she sheds her human-like body and turns into an incredibly enormous demon. Mark relates her words to Callie. Callie also turns into her demonic form, which is much smaller than Lillith's. She attacks Lillith but is eventually trampled under Lillith's foot. However, Callie breaks open a chasm and Lillith falls through it to Hell. She seems motionless after hitting the ground, possibly meaning her death. Aldermach comments that he is happy to see her gone.
Lilith is shown to be a very vile, violent and evil personality as seen by her actions on her mother. She is also shown to be very rebellious as she wanted to marry Twayne Boneraper only when Callie told her that she didn't want her to marry him. She later told Mark that she will kill Twayne and marry Mark instead, while mockingly calling him Daddy.
Lilith, by large, resembles her older sister, Callie but with a different hairstyle, longer horns, larger breasts and smaller waist. Her outfits change during the story, spaning from a grade schooler's uniform to a tight, skimpy, sexy, revealing black dress. She also wore a revealing wedding dress at her wedding.
- The way Lillith knocks Rosie off the balcony is a parody of what Damien does in the movie The Omen.
- She looks a lot like Desdemona in the game Ugly Americans: Apocalypsegeddon.
- Like her sister, she has a sexual interest in Mark.