Guy's Behavior

A guy flirts with me but sometimes calls me sis. Is he interested?

A guy in my class flirts with me all the time, he just stares at me and when I am sitting on my desk he comes up from behind and places his hand on my desk as if a back hug he always comes so close. one time he even caressed my hair when we were talking. when I am talking to some of my friends he comes beside me starts acting like he is listening and goes umhhh umm yeah... Go on And tries to annoy me. He cheers for me when I am in some competitions and goes "my name will surely win" . All of my friends tease me with his name and tell me that he is interested even people I don't talk to ship me with him and come up and tell me that we look so cute together and that he looks like he likes me a lot but the problem is when he wants me to do something for him he calls me "sis" sometimes. He once wanted notes and he said "myname sis please do it for me pleaaaaaaase I will call you sister please " . He sometimes does this but calls me sis only when he wants things done but he also flirts at the same time. I like him a lot but I am worried that he just sees me as his sister. Is he interested? I am really confused I don't know what to do. I want to confess but i am scared.

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Extra info ( how he flirts): he always leans closer when we are talking. He sometimes gets angry when I am talking to other guys. For example once a guy from my class asked him my Instagram handle and said that he wanted to talk to me and found me interesting and said that he wanted to ask me out but then he replied to him saying she doesn't like to be bothered. then the other guy again requested for my id saying he would ask me for homework but then he refused to give it to him and said that he
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Continue... doesn't need to bother me. I wasn't present when this happened but my friends were there and this was the talk of the class for days. After that if he ever saw that guy trying to talk to me he came in the middle and started initiating another conversation. He also got mad a guy when he was playing with my hair. He once accidentally said loudly "ohh yes me and my name we are in the same team. I get to be with myname " which was heard by everyone and was also the talk of the day for
A guy flirts with me but sometimes calls me sis. Is he interested?
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