Adventure might be a theme. Imagine them going on wild adventures together in the world created by the fanfic writers. It could be really exciting and full of unexpected twists. Another possible theme is competition. They could be in a friendly competition within the story, like a gaming competition or a challenge to see who can achieve something first. This can add a lot of tension and fun to the fanfic.
In 'cutiepie and pewdiepie fanfic', a frequent theme is probably mutual support. Given their popularity, fanfics might depict them supporting each other through tough times. For example, if one of them is facing a difficult situation in the story, the other comes to the rescue. There could also be themes related to their individual quirks and how they interact with each other because of those. For instance, if cutiepie has a particular way of doing things and pewdiepie has his own style, the fanfic could play around with how they blend or clash their styles in different situations.
If you want the clearest chapter reference, go to Chapter 222. Early on, How come they're even live streaming in a reality show?!; later, the chapter leans on LOL, the expressions on these people, each one more skeptical about life....
A practical answer is Chapter 283, because it turns the idea into a concrete scene. The chapter opens with Shen Lan furrowed her brows as Jiang Shixu suddenly appeared before her., adds pressure through From now on, keep that woman away from me, don't let her show up in front..., and ends on He.
The best chapter pointer here is Chapter 221, "No Choice, He Gave Way Too Much". It opens with Many agricultural students found themselves with tears brimming in their... and closes on As a result, the production crew of Shanbian Company was frequently....
If you want the clearest chapter reference, go to Chapter 235. Early on, Chasing Wind Youth was clearly becoming anxious, and as a result, his...; later, the chapter leans on I, I didn't, I'm not, I, I haven't been involved in illegal activities in....
Chapter 259 is the strongest chapter-level answer because it starts from While the villagers of Chixia Village were all immersed in the revelry of... and follows through on It wasn't that he was scared..
If you want the clearest chapter reference, go to Chapter 259. Early on, While the villagers of Chixia Village were all immersed in the revelry of...; later, the chapter leans on The man with the scarred face led the team, constantly remaining highly....
The best chapter pointer here is Chapter 252, "To This Fanatic Fan, Please Calm Down a Bit". It opens with In fact, Jiang Yan's shirtless appearance this time was entirely Jiang... and closes on Aren't these few days supposed to be solely my spotlight time?" Camera....
The best chapter pointer here is Chapter 272, "Jiang Fugui". It opens with Lin Manru held the phone for a few seconds, expecting her daughter... and closes on So, they made him a temporary ID card, temporarily changing his name to....
The best chapter pointer here is Chapter 269, "Hello everyone, let me introduce my dear niece to you all!". It opens with The next morning, Shen Lan's personal account posted a Weibo. and closes on At that time, people guessed it was Shen Lan, and there were even photos....
Look to Chapter 223 for the clearest answer. It begins with So, for the first time, Jiang Yan, who had always styled himself as the..., keeps building through My good little sister, I'm begging you, help me figure out how to avoid..., and lands on The damned Jiang Li was tricking him again!.