Why do people open up to me so easily?

I do not understand this I will talk to some one for 5 minutes and they want to be friends. I have had people, usually girls tell me their secrets and after say I can not believe I told you that, then proceed to tell me more secrets. It gets annoying with girls as after that I get wedged into the friend zone, as girls only tend to tell this stuff close friends, yet I have only known them for an hour. I feel as if I did nothing to encourage them to open up to me. I have had situations were friends will get into arguments and both will call me out to be on their side, even if there is 10 other people they know as well as me around or both come to me to badmouth the other, even if I am not involved in any way.

I also tend to end up as the leader of everything even if I don't want too. My friends have set up trips to movies, the mall etc People come to me with their questions instead of the one who set it up. Even at events at our university when the older kids are in charge people seem to assume that I am one of the leaders, though most people know I am in first year like them.
Why do people open up to me so easily?
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