Chemistry

I believe, we as people all have a certain type of chemistry, and it allows us to interact with other individuals. We all have different personalities, and our chemistry allows for us to have good interaction with certain people, while others we have bad interactions with.
I wouldn't say we just have positive, and negative chemistry, because we're all very different.So it really depends on the people, and how you get along with them.

Chemistry is something that allows us to be best friends with one person, but worst enemies with another.
I really pay attention to chemistry when becoming friends with someone. Of course, becoming friends with someone can be automatic, but for me I have to have a certain feeling, and want to be around someone. Where as other people, I don't have much of an interest in being around them.
For instance, my best friend at my current job,  right from the beginning we had a good chemistry, and now we are best of friends. We don't have many of the same interests, but we get each other, and sometimes, that's all that matters! But meanwhile, there are other people at my job that I don't really talk to because, we just don't click. There are also others where our chemistry doesn't fit right away, but it slowly starts to fit in and we can become friends only after time has passed.

I think that we have more levels of chemistry too, such as having a different level of humor, or even how you act with one person and another.
I have one friend whose humor that is similar to mine, and we are the best of friends, and both make each other laugh like there is no tomorrow! However, I also used to have a friend where we did not have the same humor, and I thought she was being really mean to me, but in reality, she was joking. Our level of humor didn't match, so I just found what she said was insulting. (Which was one of the reasons why we stopped being friends with her).
Chemistry levels also change how you can act towards one person, and a different way to another.

For instance, I had a friend who was silly and cool towards me, but with his other friends he was a total jack-ass with.
I also have a friend who is so far the only person I have been friends with, where we insult each other, but we know we are both joking, and our chemistry matches in that field of humor.

EDIT: As of 2018, I have a job where I have no chemistry with the supervisor. We just don't get each other, and she tends to lash out by being rude to me. She sometimes gets mad at me for being serious when she made "A joke", but what she said wasn't funny! Any time I've tried to joke with her, she looks at me like I have five heads!