I've been letting things whirl around in my brain blender today.
This is what I believe: everyone has some flow and ebb to them. That stream of self is changeable in some more than others - what I'm talking about is just the basic personality, as influenced by mood and outer stimuli - but no matter how much up and down you have in you, it all wraps around a central core - the person that you are all the time, in the heart of you.
Don't mistake me - I don't believe that there is much inside a person that is not subject to change. I gave up the belief in the static soul at about the same time as I lost my desire to have one (whenever that was). It's just a matter of degree: making changes in your top levels is fairly simple to manage, but once you get down to that core, changes become difficult, and powerful, and important. They are not to be undertaken lightly - and that's if one is able to consciously make changes down in the depths at all. A surface change would be to finally decide how your new haircut will be; a core change would be falling in love.
Some people have a lot more of up and down covering their surfaces than do others. That isn't wrong; it isn't right: it simply is. These are the facts of ourselves. It's just a facet of mentality - and like everything else in your mind, so long as you can function with it the way it is, and be happy at least some of the time, it ain't broke.
I'm sure this is hardly a revelation to anyone - it's certainly been kicking around inside my head for ages. It's just chosen now as the time to leave its inchoate form and come out in neat sentences. :)