Origination Storyline?

I've been tossing up the concept for a few days or so by this point and was curious as to what everyone else thought on the matter. Because the name itself implies a very secretive nature, and, to add to the role play aspect, the abyss underground could in essence be a group of citizens who live both within and outside the Abyss city...but the question is why organize?

The suggestion comes here, if it's underground, what are the citizens underground from, for?
Have at it and give your ideas!

Well, the Underground is meant to be a city, much like the Abyss, in that it takes place in TAC while not actually being part of it, so perhaps it could be a literal underground or a dimensional overlap since the Abyss doesn't have a finite or discrete location. Which is to say that once we know what it is that we're looking at having the underground become, we could also discuss exactly how it was created.

I would like to throw in a suggestion as well for this matter. Have it, so to speak, like a meeting of sorts where we all group together and discuss where we originated from, not just from Abyss but like say for instance, Perfect came from England, she eventually grew up and left England to seek out a different form of life, being that she was turned to the pyre's world and given a new frame of mind, and found Abyss out of chance. Yanno what I mean? Have it so all our charries can interact with one another, putting aside differences such as feuding against one another during their stay in TAC and sort of learning of others history in a RP style meeting for all who come here to TAU. I just thought I'd throw in my two cents I hope you understand what I'm saying lol