I'm more into stories where the reader character has a genuine ideological clash with him, not just a romantic one. Think about it: he's a twisted version of a hero, convinced his horrifying methods are a form of divine justice. A great plot could have the reader as a surviving Kai from another universe, one who understands the godly hierarchy he perverts. The tension wouldn't just be 'will they kiss,' but a brutal philosophical war. The reader could try to expose the flaw in his 'zero mortals' logic, not with power, but with theology he can't dismiss.
That kind of story lets you explore his character beyond the smug facade. You could have moments where the reader's arguments actually get under his skin, forcing that perfect smile to crack. The relationship becomes this dangerous game of intellectual seduction and mutual corruption. Does the reader start to see a sliver of his point? Does Goku Black, in some warped way, begin to respect his 'prey'? That's way more interesting than another 'enemies to lovers' template.