Proverbs 18:24 says: There exist companions disposed to break one another to pieces, but there exists a friend sticking closer than a brother and Proverbs 17:17 says: A true companion is loving all the time, and is a brother that is born for when there is distress.
From the beginning of time, it has been apparent that most people need to be in the company of and/or to feel loved or accepted by other people. Some bond quickly and go on to build on that first burst of friendship by sharing, loving, trusting and hoping it will survive the fires of all imperfect relationships. Others are acquaintances that over time become a constant in our lives. Some fade into history after a period of time that leave you with good memories but for some reason, what was needed from the friendship isn't needed by either party any longer. No hard feelings; just a case of lives moving along different paths.
I'll have to say that I've been blessed with many close friendships over the years. I have "friends" who are not anything "like me" as far as our age, sex, family, history, racial/cultural backgrounds or experiences. Whatever the differences, many times it was exactly those differences that drew us to each other and we "hit it off"! Many people have come in and out of my life and helped me grow in so many ways.
Think about your many friendships - how many times have you felt you gave more to the relationship than the other party? If that happens, you can make a decision to either continue being a good friend because of the benefits you glean from the relationship (which is more than okay) or you let it die under the weight of the other person's lack of interest.
In any case, there are very, very few that we trust completely and they are precious and worth fighting to hold on to. I treasure all my relationships and feel that as a rule, I treat most people the same. I am outspoken and cut up with everyone. If I'm misunderstood and find I have hurt some one's feelings I am sincerely sorry because I would never deliberately make someone feel bad. That is because I am constantly looking for the positive and not the negative. Thankfully I am still surprised by people who are the opposite of that and want to scream to them CAN'T WE ALL JUST GET ALONG?