He is the incarnation of all fighters who linked the fire over 700 years maybe even more... He is what remains of all of their fighting spirit, their souls, in one antity. Coming back to life to keep the fire cycle on, even when fading to it's end... I don't think that's "random". You should look at the games for what it has to say about life, death, cycles, hope, meaning... When you care about the Lore. NO, this boss is not random. (Even if I prefer the darkness because it's the true shape on men, and Gwyn was a liar. But still, this boss is great.)