How to tease a unsmiling little brother?

I feel that this unsmiling little brother is the most difficult to tease. You don't know where his personality is like a show. Maybe your body inadvertently moves, or inadvertently adds a sentence, you may touch a certain point. Maybe at that moment, his affection for you will be generate, but it is also risky. Maybe it means that your little brother is disgusted with you.

I feel that the first thing you should do is to know what this little brother likes. For example, know what kind of movies he likes, what books he wants to read, which stars or writers he likes, and then you can find some points through these to see what good movies and books are available, and what you can watch if your little brother likes to watch. Then in the process of chatting, you can casually say that you like a movie, and then he finds out that he likes it too, and then you two can start a topic and talk about something that you are both interested in. Or you can surprise him. He said he liked a certain director's work, so you said you didn't like the film. What do you think are the shortcomings of this film? Then introduce him to another movie. When he saw it, he couldn't wait to share it with you and say something about the two of you.

So when you treat this unsmiling little brother, you can't tease him in the original way. You must find out what he likes and is interested in by surprise, so that you two can open the topic and continue to talk.