Often, there's the theme of friendship turned into something more. Since they are both important characters in the Harry Potter universe, their backstories and how they've been affected by the events in the books can play a big role. There may also be themes of secrecy and the challenges of a relationship in a world full of magic and danger.
One common theme could be the exploration of their complex relationship within the wizarding world. Another might be the struggle with their own identities and how that affects their interaction.
Common themes may include the power of love and attraction in a magical setting. Their unique personalities, with Sirius being more impulsive and Lupin being more reserved, can lead to themes of opposites attracting. Also, the theme of loyalty to each other and to their friends, as they are part of the Marauders, might be explored in these fanfictions. Fanfic writers might also delve into how the wizarding society's views on relationships like theirs could impact their story.
If you want the clearest chapter reference, go to Chapter 159. Early on, Seeing the red light of the camera turn on, Su Yinwan looked at the...; later, the chapter leans on Sorry, director, it was my staff who didn't arrange things well, that's....
If you want the clearest chapter reference, go to Chapter 103. Early on, Jiang Yan looked at Zhao Lang with suspicion, eyeing the dark substance in...; later, the chapter leans on It's not going to make my face fester, is it?" Zhao Lang smiled, "Do I....
If you want the clearest chapter reference, go to Chapter 119. Early on, What is Princess Wen talking about?; later, the chapter leans on I can't understand a word?] [Is this some new meme?] [!!!.
If you want the clearest chapter reference, go to Chapter 117. Early on, Fragrant and cloyingly sweet potatoes and corn were out of the pot, and Qi...; later, the chapter leans on The searing heat made him grimace in pain, but he didn't let go, and he....
A practical answer is Chapter 115, because it turns the idea into a concrete scene. The chapter opens with Jiang Yan was woken by a loud crowing noise., adds pressure through Looking back now, the rebelliousness and obstinacy in his bones were..., and ends on [Pure bystander, wasn't Jiang Yan.
If you want the clearest chapter reference, go to Chapter 118. Early on, At 8 in the morning, several guests appeared on time next to the...; later, the chapter leans on Seeing the five individuals walking together in unison, Director Sun was....
Look to Chapter 144 for the clearest answer. It begins with Ordinary people would have been at a loss in this situation by now., keeps building through But Jiang Yan was, after all, Jiang Yan., and lands on He then noticed the hand—fair and slender, not at all like an auntie's..
The best chapter pointer here is Chapter 132, "Looking at me with that kind of eyes, are you afraid I'll eat you?". It opens with The new girl in the live-streaming room went crazy. and closes on He stir-fried the other dishes Jiang Li had prepared, and somehow managed....
The best chapter pointer here is Chapter 136, "Jiang Li Can Actually Draw Talismans?!". It opens with A few people retraced their steps back to the place they had just been. and closes on Aunt Ying and the camera PD arrived soon after..
The best chapter pointer here is Chapter 107, "Are You Really Going to Participate in That Variety Show?". It opens with On the plane, when He Yun had taken off his mask and greeted her... and closes on Although Su Yinwan's recent change in temperament had been hard for her to....