You can try fanfiction websites like Archive of Our Own. There are often a lot of user - generated fanfictions about various topics, and you might be able to find mz ruby lemon fanfiction there.
The human boy might be a lost traveler who accidentally enters the world of Sly Cooper. He is scared at first but quickly adapts. Sly sees potential in him and decides to train him in the ways of thievery. The boy has a natural talent for stealth, which he developed while trying to survive in the wild on his own. With his help, Sly's gang is able to pull off a heist that they previously thought was impossible, stealing a valuable artifact from a heavily guarded fortress.
A fanfiction of Sly Cooper and Carmelita getting married could be full of twists and turns. For example, just as they are about to say their vows, one of Sly's old foes could show up with a plan to disrupt the wedding. But Sly and Carmelita, being the strong characters they are, team up to defeat the foe and then continue with their wedding. Their relationship has always been complex, with Carmelita chasing Sly in the past. Now, as they get married, it symbolizes a new chapter where they are on the same side, facing the future together, and their love overcomes all the past differences and challenges.
One common theme is the struggle between their two worlds. Sly being a thief and Carmelita being a law enforcer. Their love has to overcome this huge obstacle.
Well, there's 'Ruby and Lemon's Friendship' which focuses on the unique bond between Ruby and Lemon. It shows how they support each other through various challenges in a very heart - warming way. The story is beautifully written with vivid descriptions of their relationship.
It could also be a key to a locked area that holds important information. Maybe it's the key to a room in a museum or a secret lair where there are clues about Sly's family history. Carmelita might have unknowingly had this key, and Sly getting it from her could be a major turning point in his quest for knowledge about his past.
One idea for a Sly Cooper fanfiction involving a human girl could be that she is a skilled thief herself, perhaps from a different part of the world. She crosses paths with Sly and his gang during one of their heists. At first, they are suspicious of her, but she proves her worth by helping them outwit the guards in a highly secured museum. As they continue to work together, Sly starts to develop feelings for her unique charm and courage.
One idea for a Sly Cooper fanfiction involving a human boy could be that the boy is a huge fan of Sly Cooper's adventures. He somehow stumbles upon a relic from one of Sly's heists. This relic has some sort of magical power that transports him into Sly's world. There, he has to learn how to survive among the various animal characters and, in the process, he becomes an unexpected ally to Sly and his gang, helping them outwit the bad guys in new and creative ways.
The OC could also be a long - lost relative of Sly. Maybe they were separated when they were young. As they meet again, they have to figure out how to work together while also dealing with their shared past and the secrets it holds.
Archive of Our Own (AO3) is also a great place to look. There are many different fanfictions there, and you can filter the search results to find specifically female Sly Cooper fanfictions. It has a large and active community of writers and readers, so you're likely to find some hidden gems.