Adora Belle Dearheart is introduced in the novel Going Postal. She is the daughter of Robert Dearheart the inventor of the Clacks and sister to the deceased John Dearheart who has been murdered to prevent him starting a rival Clack network after his father lost the original network to the unscrupulous business magnate, Reacher Gilt. Because of what has happened to her father and brother, she is a cynical, angry, chain smoker, whose whereabouts can be determined by asking the tobacconists, or simply finding a huge cloud of cigarette smoke and heading toward the middle of it. In spite of all this, Moist von Lipwig falls in love with her; an affection which she gradually returns over the course of the novel. Moist's nickname for her is "Spike"; a name she suits more than that suggested by the combination of her forenames, Adora and Belle (adorable) or her surname Dearheart. She gives Moist fair warning about making fun of either, which, given his own name, he has no intention of doing. The nickname given by her late brother John Dearheart was "Killer" which apparently he meant affectionately. The only other characters who use this nickname , not to her face, are the members of The Smoking Gnu, a secret underground resistance organization of "hackers" who she supports and helps to sabotage the "telegrafic" transceivers.
Adora is the head of the Golem Trust, a job she took after being fired from the bank for unintentionally allowing forged cheques to pass unnoticed, the bank managers needing a scapegoat that wasn't them. The forged cheques had been presented by Moist in his previous life as a con man, a secret he finally confesses to Adora late in the novel. Adora is fiercely loyal to her Golem charges and makes sure that their well-being is being taken care of, as well as their rights, particularly to one day off a week. She speaks fluent Ancient Golem and is able to understand and communicate with most of the Golems, although at times must call in an expert such as Professor Flead.
Adora first meets Moist von Lipwig in the main room of the Golem Trust when he comes to get a Golem to work in the Post Office. The Trust has just been vandalized so she greets him with a crossbow, thinking he might be a criminal. After initially being rejected by Adora, Moist eventually persuades her to join him for dinner and she selects the most expensive place in town and a drink in the Mended Drum. She dresses in heels and dresses which are tight, severe and ostensibly modest. The heels serve a dual purpose as footwear and a weapon, as the obnoxious drunk in the Mended Drum finds to his painful dismay when she puts the heel through his foot. By the end of the novel, she has kissed Moist although rejecting his proposal of marriage by saying "Not yet!" By Making Money they are a couple and are married as of Raising Steam.
Adora is fearless (people who know they are in the right always have no fear), has a sarcastic sense of humour and speaks frankly and candidly, even to the Patrician himself. Vetinari appears to appreciate this character trait, to the point where he affably baits her just to provoke a response (in much the same way that a man might use a long stick, poked through the cage bars, to gently prod a tiger so as to be able to assess the results from a position of safety). Efforts to dissuade her from smoking are generally futile and any long period without a cigarette is likely to put her in quite a bad and, for the people around her, dangerous mood. The only Discworld resident known to have succeeded in stopping her from smoking is the Librarian, who does not put up with that kind of thing around his books. She has even resisted arrest from Sergeant Detritus of the Watch and attempted to assault him by trying to stab his foot with her heel. It is uncertain as to whether lack of fear, or sheer incandescent rage, was dominant at the time, but it earned her a broken heel on her shoe, a twisted ankle and a night in the cells.
By the time of Raising Steam, the Golems are organised and numerous enough to be able to do most of the administration of the Golem Trust for themselves so do not need her help as much. She therefore accepts the position of chief manager of the Clacks Grand Trunk: Vetinari choosing not to nationalise it, but rather to pass it back to the Dearheart family to manage on behalf of the city. It is likely her salary that enables the newlyweds to buy into the most upmarket street in Ankh-Morpork.
Adora's appearance, demeanour and, especially, cloud of tobacco smoke suggest to some that she may be an avatar of the goddess Anoia (and Lela before her.) This would put Moist in an odd relationship with both the goddess and her worldly manifestation, although he was, himself, the avatar of Fedecks, messenger of the gods.