Nicholaus Geibel is an exceptionally talented mechanical toy maker who lives in Furtwangen im Schwarzwald, Germany. He and his daughter Olga enjoy a rich social life, one day leading to a post-ball get-together between Olga and a few close friends. The women chitchat about the trouble of finding quality dancing partners. They dislike how few men can dance well, how easily they tire, and how repetitive their small talk is. They jokingly bring up that a clockwork dancer would be a huge improvement. Geibel overhears this and decides to give it a try, as he's not made a partner dancing robot before. At a ball thrown by Wenzel some weeks later, Geibel introduces his latest creation to the guests as Lieutenant Fritz, but as intrigued as all are by it, the women are reluctant to take Fritz dancing on account of its uncanniness. Annette, the woman who'd first suggested the mechanical dancer, is cajoled into a trial run. All is well when Fritz demonstrates to be an excellent and entertaining dancing partner. Yet as the night ages and even the musicians tire, Annette and Fritz proceed to only dance faster and faster. It's at this point the other guests realize Annette has fainted and only keeps dancing because she's strapped to Fritz. The rescue attempt sends the robot crashing into a wall and badly injures Annette. Due to this incident, Geibel ends his construction of any and all humanoid robots.
Tropes found in this story include:
- Be Careful What You Wish For: Invoked twofold.
- One of the wishes the women had for a dancing partner was that he would "not get tired before [we] do." The problem with the robot was that it just never got tired at all and could not respond to his partner's tiredness the way a human would. And so when Annette made Fritz go faster, they kept dancing and dancing well past the moment she lost consciousness.
- When Annette warms up to Fritz, she exclaims that she "could go on dancing with him all [her] life." There's a possibility she did.
- Foreshadowing: The list of Geibel's more extravagant creations provides the reader with early clues what Fritz is capable of, what its limits are, and how things will play out. Like the donkey, Fritz can dance faster (for longer) than a human can. Like the bird, Fritz has a set course and disturbing that course causes unpredictability. Like the gentleman is more than a match to three humans, so to would've two or three men acting in concert been needed to force Fritz to a halt. Then there's the dancing skeleton that brings together dance and doom. And the curious description of a "life-size lady doll" is applicable to Annette once caged in Fritz's hold.
- Gadgeteer Genius: Nicholaus Geibel's fame as a genius toy maker reaches almost all of Europe. And supposedly this means business goes so well that he can afford to indulge in his passion to create marvels for which there is no market. Among his unsellables are a mechanical donkey that trots faster than a real one, a flying bird that always returns to its take-off point, a skeleton that dances a hornpipe, a life-size lady doll that plays the fiddle; and a mechanical gentleman capable of smoking a pipe and drinking more lager beer than "any three average German students put together."
- Gone Horribly Wrong: Lieutenant Fritz was meant to be the ideal partner for a lady seeking to dance the night away. But Geibel failed to install safety devices. The robot has no way of stopping if the human partner becomes incapable of turning it off. Its strength and speed furthermore make it difficult for another person to turn the knob instead. And all of that may have still not caused the crisis it did if Geibel hadn't left the party with Wenzel early on to leave the dance floor to younger people. None of them knew what to do when Annette was discovered to be unconscious and only made things worse.
- Gossipy Hens: Olga, Annette, and their friends are depicted as such when they talk about the men at previous balls. In fact, their gossip is more important than whoever they are. No names are given during the conversation, only descriptions such as "the thin girl" and "the previous speaker". This also makes it unclear what Annette said that caused Geibel to ask her specifically to give Fritz a trial run.
- Involuntary Dance: Annette's dance with Fritz became involuntary when the mechanism to turn it off failed. Because she was strapped to it and he was much stronger than she was and the attention of all the other guests was on their own partners and the music, Annette had to keep following along with Fritz and was made to follow along when she passed out.
- I Have You Now, My Pretty: Played with. The fact that Fritz isn't acting with any plan doesn't stop the narrative from occasionally using humanizing language for it, such as when it reads that "the thing evidently did not intend to part with its prize so easily," and that "it dashed itself and its burden against some opposing object and ricocheted off in a new direction."
- Lemony Narrator: "The Dancing Partner" is narrated by one MacShaugnassy, who otherwise has nothing to do with the story. Any of the humor and indifference to Annette's and Geibel's fates is their doing.
- Machine Monotone: Fritz can only say pre-recorded phrases. They're not monotone per se, but they become monotonous from their repetition and random utterances. There's also a harsh clicking sound that stems from Fritz's throat when he bows in greeting. It's likened to a death-rattle.
- Missing Mom: Nicolaus and Olga Geibel form a two person household. No mention is made of Olga's mother.
- Nice Job Breaking It, Hero: If the other guests had not tried to free Annette themselves, or at least not as clumsily as they did, she'd have been spared the bulk of her injuries (and survived).
- Nightmare Face: None of the women want to dance with Fritz at first because they're put off by his "waxen face, staring eyes and fixed smile." These are acceptable traits in a toy, but not in something one dances with.
- Pride: Nicolaus Geibel starts off as rightfully proud of his work, but also without any sense to think things through. He creates, but he only considers what is needed to create, not what is needed to make his creations safe to use. For the most part, this isn't necessary because his simpler creations can't do more harm than any other object and his more spectacular work isn't for sale. Therefore, before Fritz Geibel never dealt with entrusting a complex bit of machinery to another and misjudged how Annette would put it to use. He punishes himself for his neglectful overconfidence by making only simple toys from then on, despite his tinkering being his passion.
- Single-Task Robot: Fritz is made for the sole purpose of being a dancing partner, to the point Geibel justifies his stiff gait with the argument he's not meant for walking. As well, while Fritz was meant to be a versatile dancing partner, by the time of its maiden voyage it had only been programmed to waltz.
- Rule of Three: Three times the cliché phrases men use while dancing are brought up. The first time they're quoted by Olga and her friends in annoyance. The second time they're spoken by Fritz when it and Annette dance, much to her amusement. And the third time is when Fritz is malfuntioning following the failed rescue attempt and remains dancing steadily, bumping into objects in its path while making small talk.
- Uncertain Doom: Annette's fate is left ambiguous. When she and Fritz crash into the wall, "a stream of blood showed itself down the girl's white frock," and from Geibel's and Wenzel's reaction it's clear that Annette's injuries are severe, but whether she lived or died, and if she lived if any injuries were permanent, goes unaddressed.
- What Happened to the Mouse?: Olga disappears from the story after announcing to the people at Wenzel's ball that her father will arrive later with a mechanical dancer. She's the only person who could've known a thing or two about her father's work when Annette was in trouble, yet nothing is said about how she reacted to it, and she and Annette were "bosom friends", so the lack of any mention how Annette's fate affected her is notable.
