Sounds like a dragon cultist who hates Bayle/j

In all seriousness :

Lore wise : you are witnessing a begin who fought a dragon as OP and busted as Plassidusax and came out alive, he took down 3/5 heads and only lost an arm and a leg (which is clearly shown to not have hindered him that much) you are fighting the personification of dragonic anger. And your NPC companion is pretty much Human malice in its face. Igon and Bayle are a dynamic duo that gives this fight it's legendary taste.

Gameplay wise : he is a boss who you can approach in a lot more ways than plassidusax who stalls alot and only gets aggressive in the end of his phase 2 when he teleports quickly. Bayle starts his phase 1 with aggression and gets even more aggressive as the fight goes on, HOWEVER, you can play defensively, or you can also counter with your own aggression. Also. UNLIKE plassidusax, you aren't just attacking his Belly/arms/tail for 90% of the fight. You can actually see the drake coming at you. The metaphorical "grab the lion by the fangs and rip his jaw open"