There was an actual event that explains why life sucks, people suck, everything sucks and why everything continues to suck.
Wait, you mean other that OUAT’s writing decisions? ^_^
It’s not an original theory, but it fits with a lot of myth structures (‘world out of balance’ via the original act of pollution). At this point, they’re pretty heavily mired up in big scale cosmology, so it would be a waste if they didn’t try to tie in the Dark One origin/Merlin story with something as “proto” mythical as a journey to the Underworld plot.
And on that note, perhaps “snuffing out all the light” is just faulty programming — the Darkness trying to get back to its conditions of origins, but the realms are closed, things are trapped where they shouldn’t be etc etc.
One could even read Head!Rumple’s diatribe about “family” always getting in the way as a metaphor for what also makes one cling to life and hope.
OR, snuffing out the light could mean that the darkness wants to make ALL realms into an extension of the underworld! Thus bringing the underworld, and the rest of dark magic, here to where the darkness is!
SFG
Keeper of Anna’s Awkward Babbling and Kristoff’s Fur-trimmed Tunic!