A lost Ds9 episode/fic idea:
Julian notices Garak starts to act weird. He’s avoiding him. He makes mysterious subspace calls. He meets Quark several times at odd hours. He leaves a book filled with what appears to be code behind in Julian’s quarters and then gets upset at Julian for looking in it.
Julian investigates. He learns how to monitor Garak’s calls. He follows him when he goes out in the middle of the night. He learns some Cardassian and spends days trying to decode the messages in the book.
Then he finally decides to confront Garak. And the lizard man is all like “Happy birthday. I know you like to pretend you’re a spy so I created a mystery for you”.