Gentle sister x bad brother
It's a fresh novel, it shouldn't be too sadistic, and the sadism is also about the male protagonist.
Yaoyao is the arrogant little wolf dog character, and Zhuzhu is the gentle and considerate young lady.
[Arrogant face] Yao: "I like you, but I just won't say it. Who told you to only treat me as your younger brother!"
[Smiling face] Zhu: "...?"