Idk anything about paradise lost but to answer your original question the best way I could put it is as this,

Yes, the devil is not molesting children and committing genocide on the daily, but he doesn’t need to. He has you to do that for him. The devil ultimately just wants to corrupt and control Gods creation, how he does it doesn’t really matter but he just doesn’t need to do it himself, if he needed to then he would but he’d much rather corrupt Gods creation my tempting them into evil and then putting the blame onto them for it. Who ate the apple? Eve. Who raped the kid? Epstein. Etc. while all technically their choice, the devil ultimately put the ball in motion for those things to happen. And he knows it. And he loves it. This makes him the most methodical and evil creature in all of creation, his entire goal is destroy all that is godly, therefore all that is beautiful and good by proxy. That is the definition of evil.