In her demonic Sin form, Lisa is skeletally thin, extremely tall and now in possession of wings, claws and a blade-tipped tail, along with the ability to breathe fire. Lisa shares her demonic form with her husband Bob. Whenever Lisa is in control of the body, Bob's head appears where Lisa's crotch would normally be and vice-versa.
Though not much is known of Lisa's past, it is known how she met Bob. At an office Christmas party, the two met and, after flirting and foreplay at the party and a bar, went to Bob's apartment. While on the elevator though, the two knocked a neighbor of Bob's unconscious and, deciding to give into their cannibalistic urges, cooked her alive, while having sex to her dying screams. After this, the two went on a cannibalistic killing spree that lasted for years.
Though the events surrounding Bob and Lisa's deaths are unknown, it is hinted at that the two killed one another. In Hell, Bob and Lisa became collectively the Sin of Gluttony. Though Bob and Lisa can eat and eat others to their heart's content in Hell, the drawback is that they are never full for long, that and everyone in Hell tastes like sulfur. This has led the two to sometimes venture back to Earth and feast upon the living.
Despite the fact they were once lovers in life, Lisa constantly cheats on Bob in life and death and seems to be the only person who enjoys having sex with Drip. Oftentimes, Bob and Lisa act somewhat like minions in Kane, the Sin of Envy's plots. Lisa also appears to be the voice of reason to Bob, or the "brains".