CoAi

Ai x Conan is the het ship between Shiho Miyano/Ai Haibara and Shinichi Kudo/Conan Edogawa from the Detective Conan fandom.

Canon
Since birth Shiho is a member of a mysterious criminal organization that tries to eliminate the young detective Shinichi Kudo, using a substance she invented, the APTX4869. Members of the organization, including Shiho, search Shinichi's home to ascertain his death. The girl, however, during the second search, realizes that her clothes from when she was a child have disappeared and since one of the laboratory guinea pigs on which she had tested the substance had happened to rejuvenate, she correctly deduces that Shinichi is a child again. However, the scientist decides not to divulge her hypotheses to her accomplices and when the Organization eliminates her sister, she decides to betray the group and assuming the APTX4869 she becomes a child again. She thus takes refuge in the Kudo house, hoping for the help of Shinichi (who has long since assumed the identity of Conan Edogawa) and runs into one of the few people who know Conan's secret, Dr. Agasa to whom she tells everything. Shortly thereafter, the girl and the professor create a pseudonym for her Ai Haibara, who enrolls in Conan's school. Ai Haibara immediately sits next to Conan and knowing that he is there too, she accepts the offer to join the group of Detective Boys. The group, at the request of a school friend, begins to investigate the disappearance of a high school student.

Convinced that behind there is the mysterious organization that made him become a child again, Conan tries to send his friends away and investigate with an excuse, but Ai smachera the trick and so the children follow him. Eventually the group manages to find the kidnappers ... but it turns out they were simply a gang of counterfeiters. Conan is surprised by the little girl's ability to use the gun. But when she is scolded by Inspector Megure and she starts crying he tells himself that she is still a child. Conan is annoyed at having to take Ai home, but as soon as they are alone, the brunette reveals that she is the creator of the substance that made her rejuvenate, and that she knows that he is actually Shinichi Kudo. Finding out that she is in the Organization by the name of Sherry, and that she too is rejuvenated by the substance and declaring that Dr. Agasa is dead, Conan becomes frightened and curses her ... only to discover shortly after that Ai he just made fun of. Later the doctor tells him the whole story.

Ai states that since they are in the same situation, Conan can understand her, but he claims he does not identify with a criminal thing that appears to hurt the brunette. Conan eventually decides to let her live with Dr. Agasa, but despite her being the creator of the substance, she cannot create an antidote without data. However, a floppy disk she sent to her sister may contain what they need, so the two go with Agasa to retrieve it. The two immediately start making fun of each other and the detective does not trust the scientist.

Unfortunately, when they arrive at the house of the man to whom Ai's sister had sent the disk, they find him dead. The two suspect the Organization, but then Ai becomes convinced that it was an accident and tries to persuade Conan that it is so, but the confidence with which he claims that this is a murder disguised as an accident, displaces her. Eventually Conan proves it was murder, to Ai's amazement. Shortly after Ai, she bursts into tears asking Conan how it is possible that one with his deductive skills did not save his sister Akemi, a robber killed by the same man who made Conan rejuvenate, Gin, whom he had met shortly after becoming a child again. The girl bursts into tears on Conan's chest screaming because and the brunette thinks that for the first time Ai has shown him her true face.

Eventually the recovered CD is found to be unusable due to a virus and Ai comments that she and Conan will have to see each other for a long time to come. However, Conan stops considering her a criminal and when the Detective Boys go to watch a national team football match, Ai makes fun of Conan for his passion for watching the game. The brunette remains on the sidelines, for fear that a camera will film her, since the organization knew what she looked like as a child, but wanting her to enjoy the game too, Conan gives her his hat and takes her by the hand to the stands. Watching the game Conan comments that Ai never gets upset for any reason and tells her that he was ashamed to death to go back to elementary school, but that she seemed very calm. The girl replies that it was because she knew that he was in the class too, who was in the same situation as her. The scientist then thinks that Kudo is at the center of the project that the organization has been carrying out for more than half a century, but she does not talk about it with the detective. Conan later asks Ai how old she really is. As a joke, she tells him that she is much older than she is, but the speech falls because a bomber threatens to blow up the stadium. Eventually Conan manages to get the bomber arrested and Ai tells him she's eighteen, just one older than him and says she's just perfect for him. This is a playful flirtation that will become a habit between the two.

Fanon
Ai x Conan is a very popular ship in Detective Conan fandom and is primarily Ran x Shinichi's rival. Many fans think Ran is too dumb to be with someone as smart as Shinichi and that their relationship is dull, while Aibara is definitely more detective compatible and more mature.

Fanfiction
Shiho/Shinichi tag on Fanfiction.net