Peter Quinn was recruited by Magneto to be part of his new Brotherhood of Evil Mutants. He took the name Peeper and joined Slither, Shocker, Lifter and Burner. After failing their mission and being defeated by Captain America, Magneto abandoned them.
The group changed their name to Mutant Force and offered their services to the Mandrill and battled Defenders for him. Peeper became the field leader of the team, his powers allowing him to see his enemy's movements and plan for them. Despite being successful at first in defeating the Defenders and capturing the female Defenders so that the Mandrill could enslave them, the group was defeated by the Defenders during their third encounter. Mutant Force was arrested, but they bargained with the U.S. government and became their agents in exchange for their presidential pardon. Their tenure as government agents was short.
The Red Skull became the group's new sponsor. Now calling themselves the Resistants, they posed as a group advocating mutant rights. Slither left the group at this time. To avoid being associated with their old criminal group, many of the members changed their identities. It was later revealed that the Resistants were one of many groups that was unknowingly controlled by the newly resurrected villain, the Red Skull. Peeper now called himself Occult and wore a helmet to hide his features. The group fought Captain America again and claimed that their actions were all to opposed the Mutant Registration Act. They were soon joined by various new members, including Mentallo who posed as Think Tank. This time they came into conflict with Freedom Force, a group who ironically enough, had been another incarnation of the Brotherhood of Evil Mutants, but had now become government agents.
The new Captain America, John Walker, lost control during the battle and seemingly killed Occult along with several other members of the Resitants due to his recent violent streak as the result of the death of his parents at the hand of the Watchdogs, another group the Red Skull had formed to discredit the image of Captain America. During the fight, Quinn was seriously injured after hitting power lines and believed dead.
These injuries may have been the cause of his later mental problems: in his next appearance Quinn would never speak. Another mission as the Resistants was a failure as well, so the team changed its name back to Mutant Force, but by now Peeper was becoming afraid during combat. Mutant Force was defeated and Quinn, now calling himself Peepers, was imprisoned at The Cage. Wolverine and the Beast met him and befriended Peepers, who by now was a stuttering, nervous mutant who had become mentally unbalanced. Peepers repeatedly stabbed a prisoner who tried to kill Beast at this time. Shortly afterwards he was released and became a bartender at Satan's Circus, a bar for supervillains.
During the battle with the House of M, the Scarlet Witch changed reality, genetically altering over ninety percent of the world's mutant population and only leaving a few hundred with their powers as a result. During the aftermath of M-Day Peepers is seen with Mammomax and Erg on the run from the Sapien League, he comments that the X-Men hate them but Mammomax replies that the X-Men are heroes and won't turn them away, all three are caught and almost burned alive at the Xavier Institute's doorstep if not for the timely arrival of Wolverine and Colossus. However he becomes lost in the confusion of the Sapien League's attack and the arrival of the Sentinels, but he meets up with Outlaw who is also on her way to the Xavier Institute for the promised sanctuary. The two become caught up in the fight between the Sapien League, the O*N*E soldiers, and the X-Men all before reaching the mansion. Peepers stays quiet and out of the way of most of the other members of the 198. He is one of the mutants that receives a "tracking" chip and then later has it removed by Mr. M and follows him when he leads his exodus from the institute.
Later Peepers was seen in the X-Factor series. He is driving a car and calls X-Factor Investigations. Siryn answers and he tells her that he thinks he is being followed. He then sees Predator X and he crashes his car. As he is recovering, Predator X attacks him and devours him as he screams. Later, Siryn goes to the accident site, sees Peepers' body and is horrified.
Peeper, much like many other mutants, accepted Magneto's offer to live with him in outer space on Magneto's Asteroid M. However as the asteroid was defeated, Peeper once again returned to Earth.