Quite. Your explanation is great, too. I'll have to remember that.
And isn't that what makes the Adversary a character rather than some exposition? We have Tramst, who we can empathize with, but Oronthon is sort of a background picture so we have a frame for celestials popping up. The Adversary is a really poor-off guy, rather than a background element. All he wants is to actively not be part of Oronthon's plan, and he's been screwed into having to do so-- No Matter What. I'd be vindictively evil too, just not nearly so good at it.
Edited for grammar.
The only question is whether the Adversary really does not want to be a part of Oronthon's plan or not. I love Anne Rice's treatment of the 'adversary' if you will in Menmoch the Devil. There the devil is a willful participant in God's plan, albeit because he disagrees with the way God handles creation. He provides an 'alternate path' to salvation. I'm not saying that this character plays the same role but there certainly could be more to the Adversary's decision to 'go green' than simple self-preservation.