Mrs Oliver often assists Poirot in his cases through her knowledge of the criminal mind. She often claims to be endowed with particular "feminine intuition," but it usually leads her astray. She is particularly fond of apples, which becomes a plot point in the novel Hallowe'en Party.
In the books, Oliver's most famous works are those featuring her vegetarian Finn detective Sven Hjerson. Since she knows nothing of Finland, Oliver frequently laments Hjerson's existence. In many of her appearances, Oliver — and her feelings toward Hjerson — reflect Agatha Christie's own frustrations as an author, particularly with the Belgian Hercule Poirot (an example of self-insertion). The self-caricature has also been used to discuss Christie's own follies in her earlier novels. For instance, in Mrs McGinty's Dead, Mrs Oliver talks of having made the blowpipe a foot long in one of her novels, whereas the actual length is something like four-and-a-half feet — the same mistake Christie made in Death in the Clouds.
In Dead Man's Folly she mentions having nephews, and buying them Christmas presents. Although Ariadne Oliver is consistently referred to as "Mrs Oliver", nothing is known about her husband. An offhand reference to her marriage is made in Elephants Can Remember. In the same novel a goddaughter of hers appear.
In The Pale Horse, Mrs Oliver becomes acquainted with the Rev and Mrs Dane Calthrop, who are friends of Miss Marple (The Moving Finger); thus establishing that Miss Marple and Hercule Poirot exist in the same world. In Cards on the Table, there is a reference to Mrs Oliver's book The Body in the Library; this title was used by Christie six years later, for a novel featuring Miss Marple. Books by Ariadne Oliver and by a number of other fictitious mystery writers are discussed by characters in The Clocks (1963).
Like Christie, she is a member of the Detection Club. Christie even thought of placing a murder at the Club with Oliver being one of the suspects/detectives but it came to nothing (Agatha Christie's Secret Notebooks, edited by John Curran). Oliver also makes an appearance in Elephants Can Remember.
In a short piece in John Bull Magazine in 1956, Christie was quoted as saying, "I never take my stories from real life, but the character of Ariadne Oliver does have a strong dash of myself." The author of the article went on to state, "It is perfectly true that sometimes she works at her stories in a large old-fashioned bath, eating apples and depositing the cores on the wide mahogany surround."
- The Lotus Murder (mentioned in Cards on the Table)
- The Clue of the Candle Wax (mentioned in Cards on the Table)
- The Body In The Library (mentioned in Cards on the Table)
- The Death in the Drain Pipe (mentioned in Cards on the Table)
- The Affair of the Second Goldfish (mentioned in Cards on the Table and Mrs McGinty's Dead)
- The Cat it Was Who Died (mentioned in Mrs McGinty's Dead)
- Death of a Debutante (mentioned in Mrs McGinty's Dead)
- The Woman in the Wood (mentioned in and based on her experiences from Dead Man's Folly)
- The Dying Goldfish (mentioned in Hallowe'en Party)
- The Tendency of the Criminal (mentioned in Cards on the Table)
- Famous Crimes Passionnels (mentioned in Cards on the Table)
- Murder for Love vs. Murder for Gain (mentioned in Cards on the Table)
Even in the one novel in which she appears without Poirot (The Pale Horse), Mrs Oliver does not function as a detective, in that she rarely participates in the investigation and contributes only tangentially to the solution. In Cards on the Table, she does interview some of the suspects, and in Elephants Can Remember, she again interviews witnesses, but none of the essential ones. She is more usually used for comic relief or to provide a deus ex machina through her intuitive or sudden insights, a function that is especially apparent in Third Girl, in which she furnishes Poirot with virtually every important clue, or in The Pale Horse, where she inadvertently helps the investigators to determine the type of poison used to kill the murder victims, saving the life of another character.
Further functions of Mrs Oliver are to enable Christie to discuss overtly the techniques of detective fiction, to contrast the more fanciful apparatuses employed by mystery authors with the apparent realism of her own plots, and to satirise Christie's own experiences and instincts as a writer. Mrs Oliver therefore serves a range of literary purposes for Christie.
The true first appearance of Mrs Oliver was a brief appearance in the short story The Case of the Discontented Soldier which was first published, along with four other stories in the August 1932 issue of the U.S. version of Cosmopolitan magazine (issue number 554) under the sub-heading of Are You Happy? If Not Consult Mr. Parker Pyne. The story first appeared in the UK in issue 614 of Woman's Pictorial on 15 October 1932, and was later published in book form in 1934 as Parker Pyne Investigates (titled Mr. Parker Pyne, Detective in the USA). Within this story she appeared as part of Pyne's unorthodox team of freelance assistants. She also briefly appears in The Case of the Rich Woman, also published in the same book.
All her subsequent appearances (save The Pale Horse) were in Poirot novels:
- Cards on the Table (1936)
- Mrs McGinty's Dead (1952)
- Dead Man's Folly (1956)
- The Pale Horse (1961) — Oliver's only appearance in a Christie novel without Poirot
- Third Girl (1966)
- Hallowe'en Party (1969)
- Elephants Can Remember (1972)
"Not symmetrical enough for you?" -Ariadne to Poirot regarding bronze artwork in Cards on the Table.
"Remind me never to go to him when I'm poorly" -Ariadne to Poirot regarding Dr. Roberts in Cards on the Table.
"Roberts... A Welsh name... Never trust the Welsh!" -Ariadne in Cards on the Table.
"Have you redecorated?" (Ariadne) "No, Madame, I have moved" (Poirot) -Ariadne and Poirot in Cards on the Table.
"He does not skii!! HE'S 60!!!" -Ariadne to Robin Upwood in Mrs. McGinty's Dead.
"Have you everything you need?" (Poirot) "Oh yes, I'm perfectly well provided for. Reams of paper, oceans of ink and I'm sure Robin has gin.. What else does a girl need?" (Ariadne) -Ariadne and Poirot in Mrs. McGinty's Dead.
"Not late am I? We did say 4'o'clock?" (Ariadne) "No, Madame, I believe we said 3'o'clock" (Poirot) -Poirot and Ariadne in Mrs McGinty's Dead.
"Too old??.... How hurtful!!" -Ariadne to Poirot in Third Girl.
"Catch The Peacock! Tell the police in the event of my death!" -Ariadne after gaining consciousness in Third Girl.
"Would 4 aspirin be too much to take do you think??" -Ariadne to Poirot in Third Girl.
Representations in film, television and radio adaptations
The first appearance of Ariadne Oliver on television was in an episode of The Agatha Christie Hour (1982). In an adaptation of the Parker Pyne story The Case of the Discontented Soldier, she was portrayed Lally Bowers.
In the BBC Radio 4 plays, Ariadne Oliver has been played by Stephanie Cole (Cards on the Table, Hallowe'en Party and The Pale Horse), and by Julia McKenzie (Mrs McGinty's Dead, Dead Man's Folly and Elephants Can Remember).