Siblings usually are at times. He's lucky she doesn't play his games without asking and save over his files or accidentally break his consoles.
I would feel hurt and also jealous.
sometimes it gets better when you get older... when you become friends with your sibling it's the best
I have a feeling many people think she's annoying because she doesn't ship Jian Yi x XiXi and has a brother complex... I like her because she loves his brother and that is the most important, she's also cute... If she had the best personality and was a fujoshi but didn't defend/protect his brother so much or was a pervert I would dislike her.
Also she behaves like this because his brother spoils her and as it was explained they didn't live in the same house before so she must miss him... and she is uncomfortable with Jian Yi because unfortunately he had many weird suspicious behaviors in front of her... when they know each other better her behavior will change.
I don't liOr the little sister...she seems annoying and she looks annoying and she's ANNOYING!