Wuthering Waves: Am I the Rover's Master?

I'm no good at explaining this.

Yan Cheng transmigrated into the world of Wuthering Waves. After reading the memories of the body he'd taken over, he discovered something.

How had he become the Rover's master?! Not only the Rover's master, but also Changli's master!

Yan Cheng: What the hell!

(Sorry for any out-of-character moments.) (There is a timeline and a main storyline, but the story begins much earlier than the main plot. So everything before the main timeline is made up by the author based on their own understanding of Wuthering Waves. Please bear with me.)