Well I have friends who:

One day will be the sweetest... but the next will beat me up...
One day will talk to me forever... but the next will not even call...
One day send a hundred SMSs to see what I am up to... but the next not even one...
One day be patient with me... but the next can't wait to strangle me...
One day give me a huge hug... but the next beat me up...
One day I let them down... the next day they still wait with open arms...
One day chat with me for hours... but the next be extremely busy...
One day we get off on the wrong foot... but the next we will still start with a clean slate...
One day call me names... but the next claim they don't call people nicks...
One day be really understanding... but the next totally thick skulled...
One day will be all normal... but the next will really surprise me...
One day will feed me... but the next day will choke me...

You know what... that's only the partial description of just one friend! Imagine the whole spectrum!