system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] How resistant is Superman to demonic possession?
gpt
Not very.

Of all his weaknesses-- his vulnerability to  magic and magical things is a biggie. He has no special will power, no special ability to deflect magical affects -- it they're not a physical affect (IE, hurling a boulder magically) they're going to have their full affects.

DEmons, as magical creatures, can slip right back Superman's otherwise impervious nature to make themselves at home. Sure, Superman is a good person with a very strong moral code, so they won't run the show for long... but even a few minutes in Superman's body could spell disaster.

To this end, friends like Zatanna and others help him with protective enchantments... but they can't be there all the time, now can they?