I have said this many, many times both to myself and to a few close friends: Never trust someone who is too open the first time you meet him or her. Run away.
For some strange reason I cannot seem to take my own advice no matter how sound it proves itself to be. This particular bit of wisdom has proven true countless times for me. A year ago I was stuck in a cubicle with the most horrible person I have ever met and I had to work with her. I started out, three months earlier, as her friend. But she was far too open a person. She told me most of her life story and medical history in the first 5 minutes of meeting her. She seemed funny and fun-loving. So I ignored my qualms about how much information she gave and tried to befriend her. Little did I know that in only one month I would be hiding in the bathroom every chance I got just to have some peace. Of course, the bathroom being one with stalls that you have to come out of when someone else needs them she would find me in there. And if she found me in there she would take that as an opportunity to start a fight. My workplace was not safe for me anymore and people even started to mock me behind my back. Apparently I was weird because I had a colored frog toy that shone with pretty lights when you squeezed him. He sat on my desk. Soon the whole company knew about my toy frog. I also got in trouble with said person for "yelling" at her. Now, if you have ever met me then you know I cannot actually raise my voice to a yelling level. But, yes, I did tell my co-worker that she was disrespectful and unprofessional. I believe I used the phrase, "There is a line and you crossed it," once as well. I tried to get her to understand that getting her work done was the most important thing. It did not go over well.
Sadly, that was not the last time I disobeyed my own admonishment. I have done it again! I am not going to tell the story, because it would be unprofessional and disrespectful to do so at this point. But I want my audience to remember my words. You cannot trust people who give too much away at the first hello. If you want to try to be friends with them do so at your own peril. Even if the person turns out to be nice (and many of this type of people do turn out to be nice) he or she will inevitably abuse your friendship. The person who is careless with the things that are dear to her is even more careless with the things that are dear to other people. Friend is a title to be earned, not bestowed. Do not give in to the temptation to call someone your friend before the "getting to know you" portion of the relationship is over. Especially if the person starts referring to you as his or her "friend." That early into the relationship it's just not appropriate to bring up the f-word.
I am reminded of an episode of Seinfeld in which Jerry's new friend asks Jerry to help him move to a new house. Jerry goes on a long rant about how he does not feel that the relationship has reached a point where the other guy can ask Jerry such a thing. It's supposed to be funny, but it is so not funny when you have something like that happen to you. So watch out.
Oh, and if you're reading this then I'm not talking about you.