This is incredibly hot, I have to say that first and foremost. Another thing I love is how you keep making references to what defines these characters in canon - Rokurou only cares about fighting and his honor, Velvet only cares about her vengeance; yet, both can find something more in each other. You've done it well, both the emotions and the physical sensations captured perfectly. Plus, the detail where falling in love with your own benefactor is a disgrace among Rangetsus is a nice touch, I never thought of that but it would make perfect sense.

The only thing is, you could REALLY have benefited from a beta reader…or, you know…actually proofreading the story once. I see this all the time on this site, it seems; the raw talent for capturing characters and emotions and experiences, but a struggle to grasp the basic nuances of written English. I would volunteer to Beta it myself so you can update this into a more grammatically correct version, but something tells me it's too late for you to care about that. XD

In any case, I enjoyed this tremendously, and will enjoy it again in the future, probably many times to come. Long live RokuVel! :D

I loved it! Trust me, it’s in my list now, so it Will be devoured at least 8 more times this year
I love it, I love you, and, your big sexy brain! We are WiFi sole mates now.

Other than minor grammatical mistakes, the story is really well built and fleshed out. Character personalities are in line, and that last scene with Magilou made me laugh my ass off. Good job, man.