... Specifically, how they affect moral culpability, and the ability to atone for the same.

> Having a deus ex machina undo the deaths of the villains involved doesn't change the fact that CSFB! willfully killed them.

Yes and no.

On the one hand, his previous intent and willingness to kill remains an issue that he'll need to come to terms with, but the actual deed itself is negated, regardless of who manages to do so, once the retconned reality is itself retconned.

If you look at it less as a genre convention and literary device, and more as a fact in these character's lives, the retconning of Dream's actions here opens up a tremendous opportunity for debate on how responsible he can be considered anymore, when as far as his victims are concerned, they were not merely brought back to life, but no harm was ever done against them by Dream in the first place.

After all, the circumstances under which Dream did murder them in the retconned reality are almost incapable of being recreated in the "real reality," so from that standpoint, it's hard to even hold Dream accountable for attempted murder.

Of course, Dream knows what he did in the retconned reality, and he now knows what he's capable of, if someone kills one of his loved ones, but to what degree should he feel guilty for murdering the specific individuals that he did, when those murders literally have no consequences on their lives whatsoever?

A huge part of how we measure "right and wrong" is in terms of "wrong" done to others, which is part of why we don't punish "wrong" thoughts, but ultimately, the wrong that Dream knows that he did to these people in the retconned reality is no more real to them than "wrong" thoughts would be.

Which is not to say that he won't feel a need to distance himself from the wrong that he did to them, if only to set the balance straight to his own satisfaction - and I think I've come up with a reasonably creative and constructive response on his part - but if that need to make up for his misdeeds in the retconned reality matters more to him than it does to his (no longer) victims, then I can't help but wonder if his guilt over his actions is, in a very literal sense, self-centered in nature.