User blog comment:IamJakuhoRaikoben/Chapter 410: Memento Mori, Review./@comment-4449950-20141123060745/@comment-7418318-20141123085209

I think from this chapter's information we can now savely infer that the One Magic is a composite of all kinds of magic (light, dark and everything else) and thus not found in the deepest darkness as Hades assumed. Which is pretty much what I believed before already, but it's nice to have more support for that theory, even though I wouldn't call it proof just yet.

BUT there is one sure confirmation that we got. The One Magic isn't love alone, as Lucy believed, but also contains negative things. That in turn might lead to some interesting developments for the future.

I'd be nice if Lucy (could be anyone, but with her speaking about it with her mother and such, Lucy seems like the natural choice) had to go through some darker emotional states to gain access to the One Magic, but in turn would have to overcome whatever plunged her into darkness first. It's hard to explain what I mean in words without writing half a story about it... but I think it'd make an intersting bit for FT to have Lucy become temporarily darker in nature and eventually be brought back "to the light" by her comrades. But considering how caring and good-hearted she is, she'd have to be put though some seriously sick stuff to make her go down a dark path.