The fins do not change once they grow out, it is just as the fish are growing out the fins stay more female like until the fish gets big enough to start becoming a dominant fish, then his fins will finish growing out and become more pointed. I've seen it occur in my tanks, I have an Ngara Flametail who was a dominant fish in one tank, his colors glowing and his fins were always flaring out. Then he became sick and was being picked on heavily by some of the other fish. So I moved him to another peacock tank. I thought he was going to die, he looked like he got bloat and he did get ICK. So I treated with metro and he survived, but he is now a sub-dominant fish in that tank. The fins remained the same however his color completely vanished...I am working him back to dominant status though as he is eating very well now but the coloring is still on the faded side.
I also had a dominant Ruby Red that I placed in a tank with another larger dominant Ruby Red. After several weeks his color completely faded out as well and I now have him in the same tank as the Ngara Flametail. It seems that I have an aggressive tank and a lesser aggressive tank of peacocks... But the lesser aggressive tanks fish are smaller than the aggressive tank maybe by 1" or so. So I imagine that this tank too will turn into an aggressive tank once the fish mature more...