Hi Pari,
He is playing.
There are guys who like to play with girls because they know that this will often make the girl uneasy and unsure about why the guy keeps doing this.
It is often a way for the guy to exert a degree of control over the girl’s thoughts and emotions.
Indeed, there is a part of him that wants to flirt with you.
This is the side that you see when he is drunk and starts becoming very touchy and frisky with you.
When he is drunk, he is not as guarded as he normally is when sober, due to the alcohol.
Hence, that side of him that does want to flirt with you comes out.
However, when he is sober, he gets mean again because he has more control over his actions and he wants to get back the control over you that he may have lost when he was drunk.
It’s unlikely that he is treating you as his sister.
He wouldn’t get touchy and frisky with you when he gets drunk if he was trying to treat you as he would his sister.
You are dealing with a guy who may simply be too worried about making himself vulnerable to you if he were to tell you that he actually is attracted to you.
Instead, he would much rather pick on you because that allows him to keep his emotional defenses up and also get some pleasure out of exerting a degree of control over you.