Plus, it is one of the core themes that not everything is your own story; the twins existed next to the status quo and were never meant to solve it by themselves. They did participate in solving the problem, but that is all.
The biggest thing about Libra's Lament is that it is the closing act of
Bianca's story, the end of her journey, though not her life. (What's she going to find that'll kill her? Herself? Maybe. (The Twins dying would certainly have been a 'bad end' for her, however, which is why Balance intervened the way she did) )
This is simultaneously its greatest strength and its greatest weakness.
It put the setting into perspective, it showed just how bad everything had gotten, and showed just how much work would need to be done to 'fix' it. A seemingly insurmountable task, one that was being worked on from both 'sides' of the issue.
But it also meant that the players did very, very little that
couldn't have been done by others, of which the greatest part was rescuing the alternative Eva and Rico from nonexistence, which... really didn't
mean anything as far as the quest was concerned, since we were approaching the end
anyway. It was a very cool event, however, probably the best in the quest. The second greatest was quite likely the continued survival and integration of a number of members of Yggdrasil, which would otherwise have probably been rather rocky.
Other char-gen options would have been closer to or farther from the 'main plot' of the story, with Nightmare Child being the closest, Heart of Light the farthest, and Clockwork Queen falling somewhere in the middle.
If the twins had been given a clear, major, and difficult multi-part problem to overcome that the
twins story could have centered around?
That would have made the quest 'perfect'. As it is, however, there was no such thing, no unifying factor to make the twin's story
excellent. Even with the whole 'people will be people' theme going on you could have managed it.
'People will be people' and 'Not everything is your story' are
incredibly hard themes to do in a quest, especially to make
important to the quest itself through quest mechanics, though that is more relevant in heavily 'game'-like quests where the impact of the mechanics drive both the story and the attitudes of the playerbase. Players, both in video games, role-plays, and quests, are usually
rewarded for butting in where they aren't wanted, after all, even if the reward is usually just more information or world-building.
You didn't need a 'villain' or a 'big bad' to make it work here, however, despite Abyss Knight appearing to hold onto that position she was a tragic figure more than anything. Perhaps at the climactic fight over the remains of a splintering Yggdrasil, after which the players put months of work into proving that "Yes, there
is still hope left, let me show you, please give us the
time!" Where some members have found their hope again while others despaired further, when Abyss Knight swings her sword against Pris for the first and last time in anger... The White Reaper performs an intercept, and the climactic fight devolves into panic and fear on all sides while. Perhaps she leaves Abyss Knight alive, who still feels a touch of something - is it remorse? Regret? A memory, of the sisters she, herself, failed to save, or who failed to save her? - and she takes a step back, lowering her blade; or perhaps she doesn't, and Abyss Knight dies to the White Reaper saying 'I'm Sorry'.
Too short a summary for what
could have been the meat of the quest; eh.
You
did do a good job with what you did, and you learned from your missteps, which is really all that matters - so long as you're willing to run another quest, at any rate (hopeful look).
Still, the theme you chose would have probably worked
best in another medium. Marvel's Infinity War is a fantastic example - that movie was all about
Thanos, and indeed served to display
his 'final chapter' very well (no matter how batshit crazy he is, and how poor his imagination - infinite cosmic power, and his solution is to annihilate half of everybody at the snap of his fingers? ...
moron) - so this would have been
perfect as either a TV animated miniseries or an epic novel - perhaps even a series of children's stories, given the protagonists. Not so much a movie, I don't think; there just isn't enough time to show all that should be shown.
Because now I thought about the potential of that story and now it will linger in the back of my head and so on. It kills me .... or at least it drives me crazy. :lol