One key element is the exploration of their relationship. Since they have a very different relationship compared to the canon where Jonathan is more of an antagonist, in these fanfics, their bond as siblings or comrades growing up together is a major focus.
The setting of their upbringing is also crucial. Whether they are raised in a hidden place, or in a more normal but still unique situation, it greatly influences their characters. For example, if they are raised in a place full of secrets, it might make them more curious or suspicious of the outside world. And this in turn affects how they interact with other characters from the original story.
Another important element is how their upbringing together changes their fates. In the original story, their paths are quite different. But in these fanfics, being raised together can lead to them having different motives, different loyalties. It could even lead to them teaming up against common enemies or having a completely different view on the whole Shadowhunter world compared to what we know from the original series.
Chapter 123 is the strongest chapter-level answer because it starts from After He Yun also carefully rolled up her trouser legs and walked down... and follows through on Seeing this, He Yun chuckled softly to himself, then glanced at his own....
If you want the clearest chapter reference, go to Chapter 120. Early on, Facing the sudden and somewhat strange request from Jiang Li, Director Sun...; later, the chapter leans on But, as if by some mysterious force, he still instructed his assistant to....
Look to Chapter 106 for the clearest answer. It begins with Thinking of this, He Yun nodded with a hint of anticipation., keeps building through Alright, then tell me my fortune, what do I need to do?, and lands on Jiang Li's fingers lingered over the three copper coins, her clear voice....
If you want the clearest chapter reference, go to Chapter 124. Early on, Since there were too many points cards inside Jiang Li's barrel, Director...; later, the chapter leans on However, Jiang Li merely lifted her eyelids and said indifferently, "No....
The best chapter pointer here is Chapter 101, "Hello, My Name is Zhao Daniu". It opens with Jiang Li walked over to the slope where the two had fallen down. and closes on If you encounter any trouble in the future, you can come to me..
Look to Chapter 80 for the clearest answer. It begins with Jiang Yan and Wen Jiaojiao, one so smug he was almost ascending to the..., keeps building through And this was exactly the scene Director Sun wanted to see., and lands on arrogant princess with Princess Disease, I'm totally for it, fam.].
Look to Chapter 114 for the clearest answer. It begins with As time passed, the number of viewers in the live broadcast gradually..., keeps building through After a whole day of trending searches yesterday, the popularity of..., and lands on But just now, an uncle came and said not to give you.
Look to Chapter 126 for the clearest answer. It begins with Wen Jiaojiao initially wanted to cause trouble., keeps building through But when her gaze swept around and landed on Jiang Li, who was standing at..., and lands on The trolls lurking in the live stream immediately seized the.
Chapter 117 is the strongest chapter-level answer because it starts from Fragrant and cloyingly sweet potatoes and corn were out of the pot, and Qi... and follows through on Since entering puberty, his mother had exerted strict control over his....
Chapter 99 is the strongest chapter-level answer because it starts from Seeing the man approach, one of the individuals with a long scar across... and follows through on Just as she was considering whether to practice a set of boxing, her phone....