Elected at age 18 through his father's influence, John (born Octavian) behaved more like a teenager than a Pope. Even the Catholic Encyclopedia calls him "a coarse, immoral man." His unclerical conduct became notorious, but when a group of bishops attempted to depose him, he promptly excommunicated them. He was the second Pope to change his first name upon assuming the office, the only Papal tradition he seems to have observed.
Upon his father's death, John became the secular ruler of Rome as well. In this role he suffered a popular rebellion. He called the Holy Roman Emperor to his aid, but later conspired against him.
In the midst of this unrest, John expired. Some accounts say he suffered a stroke during sex with his mistress, while others assert he was killed by the lady's husband.