I cannot speak about the changes in how they look as to be honest I do not have many art or commissions done on my characters. For some of them I even use imaged I found online as reference, so I can better transmit the idea I have of how they look.
However I can tell you about how my characters grow during the time I play them. I started back on Roleplay about 1year ago, and I created a rather simple concept for that character. The first times I almost considered quitting roleplay again as no one would seem interested in roleplaying with it, until one day I accidentally interrupt a meeting by making my way to a room I had never seen people in. That moment changed it all, I was led to another place, met other people who helped my character and it changed everything. Months later this small project I had became a beautiful story. The character grew so much due to the roleplay interactions.
I believe that we all grow a bit in each interaction we do in roleplay, good or bad. It affects our characters. And this is why I love to roleplay.