For those of you who haven't seen the manga yet I can only say Ruby is 'suprisingly' REALLY into BDSM though that wasn't the primary goal at the time.

I was laughing all the way during the particular chapter.

She -really- wants to be tied up and . . . used. When asked what her relationship with the protagonist was, she responded 'Toy'. She's begged him to order her around more than once, and responded to a gut-punch that winded her (from a doppleganger, but still) with a response that basically boiled down to 'treat me roughly like that in the future too'.

It all kinda came out of left field for me, I didn't see her having that kinda kink.