Zestial’s introduction is so good
So basically, the first two episodes and the pilot hyped up Alastor as this dude everyone knows and is terrified of, the kinda guy who eats other Overlords for breakfast (literally). He effortlessly humiliates Vox with little effort and annihilates poor Pentious twice while not even caring (Pentious even says this has happened like twenty times). The dude is treated as a real threat and his powers and feats back this up. Then Zestial shows up and Alastor's clearly all like "oh shit". He's still smiling, but his eyes show his fear, however brief. It's a little thing but this is the first time in the series we've genuinely seen Alastor alarmed or scared (heck the only other time I can recall is in the finale when Adam nearly kills him and even then he didn't take Adam seriously until then). Al then all but tells the eggs "one bad move and this guy will have you for lunch" before politely making small talk with Zestial. The two chat and in the background everyone is panicking at Zestial's mere presence, one guy choosing to set himself ablaze out of sheer terror. And all the while, Zestial is super chill and polite. Fantastic stuff. Zestial has not even done anything yet and we already know he's a force to be reckoned with just from character reactions. And it was a great choice to show Alastor taking him seriously because we know Al is deadly even by Overlord standards. Any other character and it would not have worked as well. I kinda hope we find out a bit more about Zestial in Season 2, see just what this guy can do (my personal theory is that Alastor tried to take him down when he was eliminating other Overlords, only to get folded like a deck chair, and so now he acts friendly with him). He's not necessary to the overall story but man is he a badass character.