Threaten to blow her planet up.

Oh there I go revealing my star wars geekery.

I guess the question is how much into the role are you going to get? Is this mostly just a role for the purpose of playing out an otherwise pleasurable scene or is this going to be more edgy?

My understanding is that the key is keeping the target off balance. Vary your tone of voice. Be gentle one moment and harsh the next. Keep her guessing.

I'd probably go with blindfolds, cold room, stress positions, orgasm denial, maybe a cold shower or ice in uncomfortable places and generally go with things that the two of you find edgy but not over the limits. Be mean, its fun sometimes.