A common theme is power. The dragon slayer often has to deal with gaining and controlling their power in the Highschool DxD universe. Another theme is friendship, as they interact with the characters from the original series.
One of the main themes is identity. The dragon slayer character in these fanfictions is usually trying to figure out who they are in the context of the Highschool DxD world. Also, there's the theme of conflict, whether it's with other characters or with the forces of evil in the story. These fanfictions often explore how the dragon slayer overcomes these conflicts.
In 'Highschool DxD Dragon Slayer' fanfiction, a prevalent theme is the exploration of new abilities. Since the dragon slayer is a new element in the Highschool DxD world, their abilities and how they develop are often explored. Additionally, loyalty is a theme. The slayer has to decide which side they are on and who they are loyal to, whether it's their comrades or some other power in the story.
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....
The best chapter pointer here is Chapter 105, "He Yun, let me give you a reading". It opens with But this did not elicit any sympathy from the woman on the phone; on the... and closes on However, the next second, things took a turn..
A practical answer is Chapter 146, because it turns the idea into a concrete scene. The chapter opens with Director Sun: "???" Jiang Li smiled and said, "In the past, the show crew..., adds pressure through Otherwise, if they hog all the spotlight, what will we do?, and ends on That way, they.
The best chapter pointer here is Chapter 113, "Morning Exercise Check-in Group!". It opens with The next day, Jiang Lili was up before dawn as usual. and closes on If things are really as you say, that is indeed quite serious..
The best chapter pointer here is Chapter 89, "Brother He, how can you be so unreasonable too?!". It opens with Director Sun took a step back, "What's the rush? and closes on If anyone should be mocking her, it should be me.] Wen Jiaojiao stood to....
Look to Chapter 101 for the clearest answer. It begins with Jiang Li walked over to the slope where the two had fallen down., keeps building through Below the small hill was nothing other than a large patch of sludge., and lands on If you encounter any trouble in the future, you can come to me..
Chapter 162 is the strongest chapter-level answer because it starts from He Yun then realized what was happening and subconsciously wanted to check... and follows through on Having heard the news, Director Sun personally came with staff to pick.... The payoff is that the chapter closes with "?
The best chapter pointer here is Chapter 142, "From Enemy to Best Friend?!". It opens with The ingredients for making Buddha Jumps Over the Wall were still on their... and closes on Wen Jiaojiao immediately lit up and stepped forward to hug Jiang Li's arm..
If you want the clearest chapter reference, go to Chapter 150. Early on, Upon hearing the first part of Jiang Li's words, Zhang Cheng dismissed...; later, the chapter leans on After all, that information could be found online..
Chapter 75 is the strongest chapter-level answer because it starts from The ordinary people in the livestream were all stirred up by this scene. and follows through on But, being a half-baked practitioner is just fine..