My sister often doesn't return messages, but she still pays attention to my qq dynamics.

Personally, I think she did it for several reasons. As for which one, time will tell you the answer.

First, she likes you a little, but she doesn't like you. So pay attention to you silently and give you a little hope.

Second, I don't like you, and I have resistance in my heart. But out of a woman's curiosity and vanity, let's see if you are emotional because of her.