Something that endlessly fascinates me about Seven Deadly Sins, which I am 100% applying to the rewrite, is the potential it had to make these characters truly morally grey.
Not that the twist of them being innocent of the crimes they were accused of is bad, I think it worked fairly well for what we got, but it was also a missed opportunity to have the Sins genuinely be guilty of morally deplorable actions. Not because they themselves are bad people or had harmful intentions, but because they were driven by their own flaws; not just victims of circumstance but also their own mistakes, and the journey some of them go on to repent for what they've done and overcome the guilt of things they can't undo.
Ban's was already done the best in this regard, as he's never portrayed as a strictly morally good person (at least not at the start of the series). His original intention WAS to steal the Fountain of Youth, which is exactly what he gets tried for along with murdering the saint that guards it, which he DIDN'T do. But what if he did? What if it was Ban who hurt Elaine while trying to fight the Red Demon? Ban who is cocky before he realizes he's outmatched, before he realizes that he now has someone he cares for who isn't himself no matter how little time they've spent together. And he tries to save her, tries to make it right by giving her the Fountain of Youth, but she gives it to him instead. And he can't possibly imagine how she could think he was worth more than she was when he was nothing, nothing compared to her, especially when he hurt her (it doesn't matter that he doesn't mean to, because he still did, didn't he? And how can he ever explain that to her absent brother who she'll never see again?). And the guilt never leaves, and punishing himself through countless failed executions is never enough, because it's her gift to him that keeps him alive and somehow that makes it worse.
The circumstances behind King's crime always felt like a bit of a cop-out, with him having amnesia and not remembering who he is or the responsibilities he has or the people who need him. What if it was a conscious choice to stay away? Not out of sloth, but out of love? Out of devotion for this little giant girl who's all on her own with no one to rely on, who isn't helpless but is still a little kid. "Tomorrow," he tells himself, "I'll go back tomorrow, just one more day." And he tells himself that every day, and the longer he stays with her, taking care of her, making sure she's okay (because what if he leaves and something terrible happens to her and he isn't there), the harder it is to leave her. And then he does, because he is forced to confront the reality of his absence, and he can't erase her memory like in canon, and it breaks his heart and shatters hers and Diane is left bitter and angry, because everyone leaves and she's never enough for anyone because she's weak, because she's not naturally gifted like many of her other Giant brethren, and she hates herself, hates them for it, because why should they have so much power when she doesn't? Is it not just as much her right as it is theirs?
And Meliodas? Do not even get me STARTED on that little fucker. The series had the potential to do some truly interesting things with him, but it seemed to take on a very black-and-white narrative, more or less, a lot of the time. Maybe he doesn't feel guilt about all the terrible things he's done. Some things, sure, but all of it? No. In some ways he still revels in it. He does not feel guilty for slaughtering goddesses, because his rage against them is unending and "don't you see what they did to us?" Maybe I don't want him to be a wholly good person. Maybe I want him to be a little bit fucked up. Maybe even a lot fucked up. Maybe the threat to him ISN'T reverting back to his evil self - maybe he already is a little evil in some ways. How much moral greyness can I shove into one character? Let's find out.
TLDR; Nakaba fumbled the bag on potentially making these characters morally grey and complex, so obviously I'm going to do it myself.