Survival is a common theme. Given the nature of the game, many fanfictions will explore how Chuck continues to survive in difficult situations.
Another theme is self - discovery. Chuck may start to understand more about himself, his strengths and weaknesses, through the events in the fanfiction. This could be in the context of facing new enemies or challenges that force him to look inward.
One common theme is friendship. Female characters often form strong friendships with Chuck, like in many stories where they support each other through tough times.
Love triangles are quite common. Since both Chuck and Serena have had other relationships in the 'Gossip Girl' world, fanfiction often plays with the idea of how those other relationships impact their relationship with each other. For example, Serena's past relationships might create jealousy or misunderstandings when it comes to Chuck.
One common theme is redemption. Chuck often has a complex past in the Supernatural series, and in many fanfictions, his relationship with his mate is a part of his journey towards redemption.
One common theme is friendship. Since they are often in some sort of team or working relationship, stories might explore how their friendship develops and endures through difficult situations.
One common theme is friendship. They often explore how Chuck and Red support each other. Another could be adventure, like they go on some sort of quest together.
One common theme could be family bonds. Since Chuck and Ellie are siblings, stories might explore their relationship deeper.
One common theme is friendship. The fanfiction often shows the strong bond between Chuck E. and the other animatronic characters like Helen Henny, Mr. Munch, etc. They support each other and have fun together, just like friends do.
One common theme is the exploration of power. Since Chuck is a powerful being in the Supernatural series, fanfictions often deal with how Sam interacts with Chuck's power and what it means for their relationship.
One common theme is redemption. Since Sarah has hurt Chuck, often the stories focus on her journey to make up for what she's done, to prove that she can change and be better for him.
Another theme could be the culture clash. 'White Collar' has a more high - society, art - heist kind of vibe, while 'Chuck' is about a regular guy thrown into the world of spies. So, in the crossover fanfiction, there could be a lot of humorous moments as the characters from the two shows adapt to each other's worlds. For instance, Neal might be shocked at the high - tech gadgets that Chuck has access to, and Chuck might be in awe of Neal's refined tastes. It makes for some really interesting character dynamics.