Muffy first appeared during a police investigation. The police had come to the old office/home of Grizzly Adams, a man who had worked once with Jack Hack. Adams was also using his home to re-educate feral children in hopes of introducing them back into the civil world. What Muffy and the police officers also didn't know that Adams had used Rev-D (a more scientific term for what makes a slasher) into the children and made them more feral and carnvorous. Cassie and Vlad, had fought the two leaders of the feral children and killed them, knowing they had been basically turned into slashers and were dangerous. But neither knew that, all the police saw was a burned house with dead children. Hoping Muffy could help, Officer Hazelwood asked to use her psyhic abilities.
While she claimed she saw nothing, the truth was she saw horrific murders. However, what she saw was Cassie doing the killings instead of the slashers. In one dream, the murders that Father Wrath had committed, for some reason she only saw Cassie doing the murders. It eventually becomes clear that Ashley Guthrie is influencing her visions and making her believe that Cassie's the killer. While she believes her visions are becoming stronger because of Cassie, in some way it was most likely that it was Ashley's powers taking control of her mind. As she would later on show child like behavior.
Muffy, unfortunately, was becoming a pawn for him and Six Sixx as they needed to retrive Six's guitar to enter Earth again. Using his powers, Ashley and Six were able to influnce Cassie, Vlad, and Gertude Hall, knowing they'd soon gather with his guitar. Knowing he needed a physical body, Ashley soon cornered her in the dreamworld and caged her. When she awoke, it was Ashley who was now in control. With him now in control, he find out where Cassie and the group had been held.
He soon killed the officer, drove the car into station, and using Muffy's body to kill any officer who got in the way. As he finally found Six's guitar, he released him from his hell back to Earth. But before either one can fight with Cassie, they see that Six unintentionally brought some bizarre creatures that possessed the dead officers' bodies. The entire group was soon tied up, including Muffy/Ashley, her husband, and Six. While they were tied up, the creatures began to tortue Cassie and the group with their worst fears in their minds.
As the creatures were about to move onto Six, he broke free and quickly returned to the Nef world to restore his powers. When he returned, freeing the hostages. He announced his deal he had made with his masters. His goal, get Cassandra Hack. However, the newly freed Ashley (still possessing Muffy) didn't care he wanted Cassie dead. Seeing there was no reasoning with him, he knocked them out. He then takes Ashley/Muffy as payment to his masters for his newly restored abilities and leaves Cassie.
However, remembering the old woman, Cassie pleads to spare her. However, Six rebuffs the statement saying she's dead. She's been gone since Ashley took over.
It was eventually revealed that Muffy (or Ashley) was still alive in Nef, Murder Messiah issue. The Neflords created Stillborn, a creature formed from dream-walker Ashley Gutherie and Muffy's psychic abilities, to destroy their threat in Cassie. In addition, Stillborn, like Sixx, would be used to gain attentions of fans to feed on their psychic energy Muffy, however, would not survive the creation of Stillborn. He, literally, burst out of her womb, killing her. Its unknown if Ashley died with her or is trapped in the Nef world.