Heh... Interesting. Definitely on the macabre and dark side. The beginning and end lines are almost like an obscure equation, perhaps using the spilling of blood in context with refracted light, obscured by shadows. But then again that's just me. Definitely gives the impression of hidden meanings. Will have to read this riddle more than once, to fully appreciate it. I think it reeks of drunken logic. Both bitter and sweet. Much like the taste of hops and barley. (Wait... Which sex am I again?) My favorite part is alpha and zeta.

This is really beautiful.  I totally understand the imagery you are using here, and I think most people can relate to the emotions the narrator feels, since most of us have known people who keeps themselves hidden inside.  Tripping on a crack (figuratively or literally) is when one's actual essence starts to come out; those of us who live openly let it stay out, but many of us tuck it back in, "spilling, wheeling, unspooling, refilling."  Thus, we never truly get to know each other in the way that we should.

Anyway, even if that didn't make any sense, you can tell I love this poem.  Great job.

Great poem! To me, it's about someone seeing the dark side or "shadow" of someone they know well. I like the use of the word "unspooling," like something is coming undone and the person has no control over it. The fifth line, without any punctuation, works really well because it offsets the broken up lines before and after it. The switch between "once, or maybe never" and "never, or maybe once" was very intriguing and made me read this poem at least four more times over!