One common theme is the idea of redemption. Slade, being a complex and often villainous character, might find redemption through his relationship with Robin. Another theme is the power dynamic. Robin, as the younger and more 'good - natured' of the two, often has to navigate his relationship with Slade who has more power and experience.
Common themes in slade x robin yaoi fanfic often involve a lot of emotional turmoil. Since it's a yaoi relationship, there will be the exploration of romantic feelings between the two. Also, themes of redemption might come up, like whether Slade can be redeemed through his relationship with Robin. There could also be themes related to secrecy and forbidden love, as their relationship might not be accepted in their world.
One common theme is the power dynamic between them. Given their different natures, the exploration of who has more power in the relationship is often seen. Another could be redemption, perhaps Slade seeking redemption through his relationship with Robin.
One common theme is the struggle for control. Slade's possessiveness often leads to a power struggle with Robin who values his independence. Another theme could be the blurred lines between love and obsession. Since Slade is possessive, it can seem like his feelings cross over from just caring to being overly obsessed.
Common themes might include power dynamics. Given Slade's more experienced and often menacing nature compared to Robin, there's often a play on who has the upper hand in the relationship. Another could be redemption, where Slade might be on a path to redemption through his relationship with Robin.
One common theme is the exploration of their complex relationship. Given their different personalities and roles, fics often delve into how they interact, whether it's a rivalry - turned - something - more situation.
One common theme is redemption. Often, Slade is portrayed as seeking redemption in Oliver's eyes, like in many stories where he tries to make up for his past wrongdoings.
One common theme could be the power dynamic between Slade and Robin. Since Slade is often portrayed as more powerful and experienced, it creates an interesting dynamic in the fanfiction. Another theme might be the forbidden nature of their relationship, considering their different sides in the story's context.
One common theme is power dynamics. Slade is often portrayed as more powerful, and the story may revolve around how he uses that power to harm Robin. Another could be revenge, where Slade has a motive to hurt Robin for something that happened in the past.
Archive of Our Own (AO3) is a great place to start. It has a large collection of fanfics from various fandoms, including ones for Robin x Slade. The search function there is quite useful for finding exactly what you're looking for.
The relationship's evolution is a major element. It might start as a mentorship - like relationship in some fanfics, where Slade seems to be guiding Robin, but then it can turn into a more adversarial or a complex, ambiguous relationship as the story progresses. This evolution keeps readers interested as they wonder where the relationship will go next.