Born less than three months after the end of World War II, he was the illegitimate son of an American GI stationed in New Zealand and a seventeen-year-old girl from one of Auckland's wealthiest and most influential families. His father refused to acknowledge his responsibilities and accused his mother of being a whore. He went off to war and was killed by friendly fire two weeks later. Stevens was put up for adoption immediately after he was born.
As a child, an interest in rugby was drilled into him.
On his 18th birthday, 22 November 1963, John F. Kennedy was assassinated in Dallas, Texas. After JFK's death, he became obsessed with finding out about the man. This passionate search for the truth led him into journalism.
On his 21st birthday, his foster parents told him that he was adopted. Years later, he went to meet his mother, but left again, realising that she had no love for him. Soon after, he left New Zealand for Britain. He arrived on Fleet Street and soon found work at the Daily Chronicle, a local newspaper. He discovered that his immigration was questionable, and that he needed a British wife soon. Just to mess with the royalty, he married Natasha Howarth, the daughter of Lord Howarth. It was a well known wedding, and they even got a Beatle to attend and appear in a photo with them, making it a front page story.
While working at the paper, Stevens discovered and found himself obsessed with UNIT, "Dr. John Smith" and a history of alien intervention in human affairs dating back at least to the ULTIMA Incident in 1943, believing from available information that UNIT were a shadow organisation with an ill-defined agenda. He met Dodo Chaplet, a mentally broken erstwhile companion of the Doctor in his first incarnation. They developed a romantic relationship until she was killed by one of the Master's agents; the Master had been the source of most of Stevens' information in an attempt to create trouble for UNIT, but killed Dodo to break Stevens after his investigation threatened to expose the Master's own scheme. At her funeral, Stevens briefly met the Doctor himself — though it remains unclear as to whether the Doctor whom he met was the Second or the Seventh Doctor.
Emotionally shattered at Dodo's death, Stevens set out to confront UNIT at Auderly House, but the sight of an Ogron forced him to recognise that UNIT's true agenda was benevolent and they had only kept the truth secret because nobody would believe it.
Having travelled to Dealey Plaza on 22 November 1963 to witness the Kennedy assassination, Stevens had seen his own older self shoot Kennedy. He remained haunted by the knowledge; to ensure that history kept to its proper course, Stevens knew that he must eventually return to that time and place to kill Kennedy. (PROSE: Who Killed Kennedy)
Before leaving the present to commit the assassination of Kennedy, Stevens mentored Ruby Duvall, a young aspiring journalist, and Sarah Jane Smith, the latter of whom would become a companion of the Third and Fourth Doctors. (PROSE: Who Killed Kennedy) Ruby later fought the Cybermen in Antarctica in 2006 with the Seventh Doctor. (PROSE: Iceberg)
Behind the scenes
- Who Killed Kennedy came out with the fictional James Stevens listed as its co-author, alongside its real author David Bishop. Stevens supposedly appears in the form of an unnamed journalist in Spearhead from Space and one of the observers in The Mind of Evil played by various extras. Although it is unclear who Stevens is in Spearhead from Space — he is the journalist who manages to ask the Brigadier, "Then why are you here?", only to be told "Training exercise" (a line clearly delivered by Michael Wagstaffe) — the Mind of Evil section gives clear descriptions of where Stevens is standing and sitting. However, once again, the character that Stevens is meant to be in the story is actually Arthur Linwood, who the book ironically gave a name to as well.
- In Doctor Who and the Silurians, Stevens is the journalist with whom the Brigadier has an angry telephone conversation. Lethbridge-Stewart demands to know "The Daily what? How did you get hold of this number?" After telling Stevens, "Look, I have no comment to make. Now will you please get off this line!", the Brigadier slams down the receiver.
- Although pseudonyms have been used on many occasions, and short stories and other minor fiction have been released credited to characters within the series, this is the only occasion to date in which a full-length novel has been credited to a character.
- The character's name is derived from David Bishop's own middle names, James and Stephen. Bishop named his fictional co-author after himself to reference the fact that both authors credited on the cover are one and the same. 
- There is some ambiguity regarding Stevens' date of birth in the novel. At different points it is given as being both 22 November 1945 and 23 November 1945. This is explained in the prelude, where Stevens explains that due to the time difference between England and New Zealand, it was the 22nd in England but the 23rd in New Zealand at the time of his birth.