Working for JokerHarley Quinn as Joker electrocuted her. He later appears as Joker's body guard at a strip club. He is approached by Monster T who wanted to meet with the Joker. Frost tells him to "Sit down and have a drink." While Monster T and Joker talk, Frost is seen watching with a cold interest.
Tracking Harley QuinnBelle Reve. After telling the Joker this, he is told to bring the car out for a drive. Frost and Joker go to a casino that Belle Reve guard Griggs frequented. They pay off the casino manager, who brings Griggs to them for Joker to interrogate. Frost and Joker learn from him that Harley has been inducted into Task Force X: a team comprised of super villains who go on Black Ops missions for the government. They also learn that members are injected with Nano-Bomb implants to control them.
Assaulting Van Criss Laboratories
Frost accompanies Joker and the rest of his gang to Van Criss Laboratories, a branch of Wayne Industries that manufactured the nano-bombs. While Joker's Gang assault the lab, murdering numerous employees, Frost guides his boss to Dr. Van Criss. He startles the doctor by firing three gunshots into the lab window. Joker is able to blackmail Criss into working with them when he shows him a live feed of his wife being tortured. To ensure that he doesn't rebel, the Joker implants one of his own Nano-Bombs into Criss' neck.
- "Boss, we've got a problem!"
- ―Jonny Frost, just before Savior 10 crashes[src]
Frost is shown to be incredibly loyal to the Joker. He carries out orders for his deranged boss without question, attacking the defenseless psychiatrist Harleen Quinzel and countless scientists. He doesn't show any concern for human life; he is willing to murder anyone that his boss wants dead. He watches his boss' meeting with Monster T with great curiosity, interested to see its outcome. He warranted no reaction when the latter was killed. He has a dark sense of humor, as evidenced by his sarcastic and snarky comments during Grigg's interrogation.
- Joker's gang
- Dr. Van Criss † - unwilling ally
- Griggs - unwilling ally
- Amanda Waller
- Task Force X
- United States Armed Forces
- In the Joker graphic novel, Jonny Frost was a low-ranking thug who becomes the Joker's chauffeur and witnesses many of the Joker's most hideous criminal acts. He ultimately loses his life when the Joker shoots him in the chin and lets him to fall into a river to bleed there.
- Its worth noting that Frost is the second person non-backround character shown to be completely loyal and unquestioning to the Joker in any media, following Harley Quinn herself.
- Position of Jonny Frost as Joker's first lieutenant is a reference to character Robert "Bob" Hawkins, aka Bob the Goon, from 1989 film Batman.