Prompt 15: Exceptions
I thought of this prompt after seeing the scene of the Kaitou KID episode 2 "Blue Birthday", were it is shown how Agasa drives with his beetle away from the Blue Parrot and it's implied that he gave Jii a replica of KID's heist target or some gadget:
Conan goes to visit Agasa-hakase and sees him making a replica of KID's target the day after. He hides, before he can be spotted and in the evening he secretly follows the beetle to the Blue Parrot, where he overhears Jii talking to Agasa. In his shock he doesn't notice the professor leaving and only the jingle at the door for a new customer gets him out of it. Instinctively looking up he sees Kaito walking in, instantly recognizing him. The next day Conan attends the heist and KID steals the gem by leaving a well-made replica behind – the one Agasa made.
Distraught he calls his father, sure that Yusaku couldn't have not known about it. And as he feared, his father admits to knowing KID's identity for years. Even his mother butts into the phone call and says that even she had heavily suspected it.
Conan realizes that he's the only one left out, the only one of his family who doesn't know. Unsure how to proceed he can't stop thinking about it. Feeling betrayed and somehow even sad, he doesn't know why he's even chasing KID, why he puts that much effort into it. He's confused, because he's a detective and is aware that he should tell the police, but at the same time he doesn't really want to and wonders what his family would think, finding out that he's the reason the son of a dear friend ended in jail. He has no idea how to go on concerning KID. Should he even continue attending heists?
This story starts out with Conan, but if you let him change to Shinichi or not is up to the author (I don't mind either, but a relationship is easier with Shinichi, with him being an adult compared to Conan). I'm not sure if I managed to express myself enough to bring Conan's feelings across. Conan obviously has made exceptions for KID before, but he still gave his all to catch him with his duty as a detective. In this story he has to figure out what to follow – his moral, his mind, his heart – and that takes quite a toll on him. He feels played, wondering if KID knew all along that the Kudo family was on his side (which Kaito doesn't).
If you let KID know that Conan is Shinichi is up to the author, both sounds interesting. But if you make him already know, I think it would make Conan's thought of "KID knew all along that the Kudos are on his side" even 'worse', thinking that KID didn't actually take him seriously despite his appearance, but just didn't see him as a threat with the knowledge that he wouldn't end in jail anyway with the Kudos on his side. At the same time, Kaito has no idea about what happened.