- "Now you've done a lot of bad things in your life, but you've done one thing you can be proud of: you were a father. A good one. You were there for your son during the toughest time of his life, and that's what you need to do again now. If he kills her... you will have failed at the one good thing you've done with your life. Be a father now."
- —Supergirl to Peter Thompson[src]
Peter was a petty criminal with a record of three B&Es and two DUIs. Peter later learned that he had a son, Rick Malverne, who lived in Midvale and was being abused by his mother. Taking custody of his son, Peter moved Rick away from Midvale and did what he could to provide for them. With great difficulty, Peter was able to afford to send Rick to college, for which his son was grateful.
Helping his son
In spring 2017, Peter was visited by F.B.I. agent "Hank Henshaw", NCPD Detective Maggie Sawyer, and Kara Danvers, a reporter from CatCo Magazine. Peter was slightly confused and amused by the diversity of his visitors. They explained that an anonymous individual was demanding his release from prison, which Peter was a little surprised about. When they asked if he was keeping in touch with anyone outside, Peter sarcastically recounted a discount offer he received from J.C. Penny the previous week, setting Kara off. Kara revealed that her sister, Alex Danvers, had been kidnapped in exchange for his release and angrily demanded to know who was responsible. Peter maintained that he didn't know, but Kara refused to believe him until "Hank" confirmed it.
Later that night, Detective Sawyer arrived at Albatross Bay to break Peter out and return him to his son, Rick, who was revealed to be behind Alex's kidnapping. Sawyer used D.E.O. technology to cover their escape from the guards, to which Peter complimented her. However, they were intercepted by Supergirl, who persuaded Sawyer to stop and revealed Rick's motivations to Peter. Supergirl stated that despite his mistakes, Peter was a loving father to Rick, which is the one good thing he did with his life. She urged Peter to tell them where Rick was keeping Alex, warning him that if she died, his son would never come back from it. After some thinking, Peter told them the location of a warehouse where he thought that Rick would take her. Supergirl and Sawyer managed to get there in time to save Alex.
- It's implied the murders he caused were accidents and not out of maliciousness.