Perhaps it would be interesting to see him putting on a face or, shall we say - a farce in order to show what he wants people to think of him. Harkening back to the Pilot Alastor. The Red Menace kind. Then comes the first man and pulverises him and then adds a dialogue in the fight, perhaps making Adam more serious and Alastor at first seeming more "Ha, not breaking sweat!!!!".
But then, Alastor gets desperate, because Chadam faced people much worse than a serial killer (Imagine, how
Genrikh Yagoda would look like in this hell?) And then Alastor's mask slips and shows he is absolutely who he is once he loses control of his victims: insecure, pathetic, and anxious. And then he becomes everyone's laughing stock. The only people who weren't fooled were Lilith-probably-Rosie and Lucifer.