Well, a major theme is the power of their bond. It's often shown as something that can overcome all kinds of supernatural threats. Also, redemption is a theme. For example, Dean might find redemption through his relationship with Castiel, or vice versa. And of course, love in the face of the apocalypse or other dark forces is very common. These fanfics show how their love can be a light in the darkness.
One common theme is sacrifice. They often sacrifice for each other in these fanfics, like Castiel giving up his grace or Dean putting himself in danger to save Castiel. Another is the exploration of their unspoken feelings. Since they don't always express their emotions openly in the show, fanfics love to dig into that.
The themes usually revolve around their deep connection. This can be in the form of a soulmate - like bond. Many fanfics also deal with the theme of trust. Given the dangerous world they live in, their trust in each other is crucial and is often explored. And then there's the theme of self - discovery. Through their relationship, both Castiel and Dean often discover new aspects of themselves that they didn't know before.
A practical answer is Chapter 197, because it turns the idea into a concrete scene. The chapter opens with Seeing that no one cared about what she said, Su Yinwan immediately felt..., adds pressure through Dear brother, you've protected me all this way, why not let you handle..., and ends on Wen.
Look to Chapter 244 for the clearest answer. It begins with LOL, Director Sun can't seriously think his sappy quotes are working, can..., keeps building through Yet, Director Sun was indulged in the emotions of having moved himself and..., and lands on I don't really have much to say..
Chapter 173 is the strongest chapter-level answer because it starts from Jiang Li finally rose from her seat. and follows through on Yet Miss Su went out of her way to ask me not to be angry..
The best chapter pointer here is Chapter 240, "He's the Last One?!". It opens with Wuuuuh He Bao truly deserves it, Mom always knew you could do it!"... and closes on Right then, her face turned completely sour..
If you want the clearest chapter reference, go to Chapter 244. Early on, LOL, Director Sun can't seriously think his sappy quotes are working, can...; later, the chapter leans on Yet, Director Sun was indulged in the emotions of having moved himself and....
Look to Chapter 227 for the clearest answer. It begins with Your Four Pillars of Destiny is very strong, with wealth, authority, and..., keeps building through The comments section was filled with amazement as well., and lands on Your three palaces are prosperous, and correspondingly, your.
If you want the clearest chapter reference, go to Chapter 210. Early on, This was Zhao Lang's first public appearance.; later, the chapter leans on He was dressed in a set of black and white local attire, with a simple....
Chapter 219 is the strongest chapter-level answer because it starts from Qi Tianyu was somewhat freaking out. and follows through on Having any yield at all was already the show giving them face..
If you want the clearest chapter reference, go to Chapter 231. Early on, Huo Xuan felt a burst of secret delight in her heart.; later, the chapter leans on Huo getting angrier, she became even more adept at playing the innocent....
A practical answer is Chapter 213, because it turns the idea into a concrete scene. The chapter opens with Jiang Cheng also noticed where Jiang Shixu's attention lay., adds pressure through Director Sun, please don't tell me the King for today is me again., and ends on As soon as they were seated.