Another theme is the redemption arc for Castiel. In these fanfictions, Dean plays a crucial role in helping Castiel find his way back from any dark paths he may have tread. For example, some stories show Dean standing by Castiel during his struggles with his angelic nature.
There are fanfictions with the theme of alternate universes. In these stories, Dean and Castiel experience different versions of their relationship. For example, in one universe they might be rulers of a supernatural kingdom, and in another they could be ordinary humans. These themes add a lot of variety and intrigue to the fanfictions.
One popular theme is the re - imagining of their relationship. For example, exploring how a female Castiel would interact with Dean on a more emotional level. Maybe she would be more in touch with her feelings and it could lead to a different kind of dynamic between them.
One common theme is friendship. Their bond, whether it's a platonic friendship or something more, is often explored. Writers like to show how they support each other through tough times.
One popular trope is the 'First Kiss' trope. It often builds up a lot of tension between Castiel and Dean before they finally share that first, passionate kiss. Another is the 'Forbidden Love' trope, as their relationship within the context of the show has many obstacles, and this is often explored in fanfiction with their kisses being something that goes against the norm or is kept secret.
One popular story could be 'The Bond Beyond Worlds'. It delves into a deeper connection between Dean and Castiel, exploring their relationship in a post - apocalyptic setting. The story is known for its intense emotional scenes.
The 'alternate universe' trope is quite common too. For example, there are fics where Dean and Castiel are in a modern - day high school setting instead of the supernatural world they're usually in. It gives a fresh take on their characters and relationship.
Well, 'The Unspoken Love' is also quite well - known. It's a slow - burn story where the kiss is the culmination of many small, tender moments between Dean and Castiel. It shows how their relationship has been building gradually, like a slow - growing flame.
One popular theme is the 'friends to lovers' trope. It shows the progression of their relationship from just being comrades in the fight against the supernatural to falling in love. Another is the 'hurt/comfort' theme, where one of them gets injured or is in emotional distress and the other provides support.
Some fanfictions focus on how their marriage affects the rest of the Supernatural universe. For example, how their relationship impacts Sam or other characters. There are also themes related to their different natures - Dean as a human and Castiel as an angel - and how they navigate their married life with these differences, such as Castiel trying to understand human emotions better for the sake of their marriage.
Romantic relationships between them are also a popular theme. Writers might explore how a relationship between an angel (Castiel) and a hunter (Dean) would work, dealing with the differences in their natures, their loyalty to their respective worlds, and how they overcome obstacles to be together.