The power imbalance. Glitchtrap has this sort of otherworldly and menacing power, while Vanny is more of a human (or at least a physical being in the game world). The contrast between their 'strengths' makes their relationship in the fanfic really captivating. It's like seeing how a small, perhaps vulnerable character gets caught up in the web of a much more powerful and devious entity.
The mystery surrounding both characters. In the FNAF universe, there are still a lot of unanswered questions about Glitchtrap and Vanny. A fanfic that pairs them can use this mystery to its advantage. Writers can come up with their own theories and explanations for their relationship. For instance, they can explore how Glitchtrap came to be and how he managed to get Vanny on his side. It gives the writer a lot of creative freedom and the reader a chance to explore different interpretations.
If you want the clearest chapter reference, go to Chapter 46. Early on, Upon hearing this, everyone but Jiang Li perked up with high alert.; later, the chapter leans on After all, there were only a few who didn't care how others saw them..
If you want the clearest chapter reference, go to Chapter 19. Early on, What criminal law is this or that, this was originally none of your...; later, the chapter leans on In high school, she got into the international class by throwing money....
Chapter 846, "Locked up for 6 months!", is the clearest early answer because it turns Jin Siyue's situation into a concrete plot event. Early on, She took a deep breath, and a guilty expression immediately appeared....
Chapter 47 is the strongest chapter-level answer because it starts from Qi is actually second???] [Did the production team make a mistake? and follows through on Qi is so excellent and only got 17, yet Jiang Li comes in with 22?.
Look to Chapter 25 for the clearest answer. It begins with Therefore, from his childhood, Jiang Shixu had felt an extreme aversion to..., keeps building through Over time, he naturally developed a gap of estrangement between himself..., and lands on Having worked beside Shen Lan for over a decade.
Chapter 826, "Deadlock", is the clearest early answer because the violence around Father Yu becomes final instead of hypothetical. Early on, The Li Family Master had spoken, so Father Yu quickly followed suit.... By the end, Yu looked puzzled, "What, you all know this Jiang Li?" Father Yu had....
Chapter 848, "Just an Adopted Daughter", is the clearest early answer because it turns Gu Qiang's situation into a concrete plot event. A useful checkpoint is the way the scene starts with With a "snap," the old lady slammed the photo onto the table, clearly...
Chapter 793, "Back After Many Years, with a Son", is the clearest early answer because it turns Jiang Shixu's situation into a concrete plot event.
Chapter 873, "The Sooner, The Better", is the clearest early answer because it turns Shuiyun Temple's situation into a concrete plot event. The chapter gives readers a real answer by opening on Under a curse?!" Wan Jia stood up excitedly.
Chapter 909, "Hexin Sanatorium", is the clearest early answer because it turns Rong Kexi's situation into a concrete plot event. The chapter turns that into something concrete by moving from Jiang Li looked at him, as if recalling something.