Early Life

John Cereus (Earth-616) from Sensational She-Hulk Vol 1 20 0001

"Jack Serious"

Dr. John Cereus is psychologist who conducted an experiment involving placing one hundred subjects in a people in a vat that could only normally hold ninety. He exposed them to a vapor that would condense the mind he dubbed, "Serious Gas". However Dr. Cereus fell into the vat himself and was trapped their for a full week. When he was released he was changed both physically and mentally losing his mind in the process.[1]

Dorkham Asylum

The other subjects were taken to Dorkham Asylum, where he now worked as Chief of Staff. He was annoyed that his theories were ignored and killed Timothy Hayes and his wife in anger right in front of their daughter Purple Hayes. He then began a long career of using the gas on people in crowds in public places.[1]

Nosferata & She-Hulk

Dr. Cereus encounter Purple Hayes again now known as "Nosferata". She teamed She-Hulk to stop a shipment of the Serious Gas and that he vowed revenge against the heroes. He sent Three Face to expose She-Hulk to the gas and kidnap her for experimentation.[2] However due to her dense skin he could not take a blood sample, so decided to electrocute her instead. Nosferata arrived to save her and learned that Serious had been the one that murdered her parents, he tried to run but lost his footing again and fell to the ground floor were he was brutality attack by the inmates.[1]

Crossmore Asylum

Cereus was later interned into Crossmore Asylum, in Doctor Whitby's section. She treated him for nine years, in Crossmore and in another institution[3]. His doctor license had been revoked after his mass murder.[4]

He was beaten by Deadpool alongside the ten other patients of the unit, and sent to the hospital..[5]



  • Psychologist: Dr. Cereus is a brilliant psychologist with several degrees.[6]


  • Cereus a pastiche of the Batman villain the Joker, and his Serious Gas is a pastiche of the Joker's Joker Venom.

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