"I'll do what you ask, but ...."

"... You must allow me to sleep with my mom first in any form, after which, she's all yours. You can erase her memory after I'm done with her. But promise me, that I'll have a chance with her after."

"That I will, my cousin. Your first part of the request will be done."

"What? But how?"

"That doesn't matter. Go and meet your mother for the last time, Dudley. Because after tonight she will be mine. "

Dudley knew he had no choice otherwise, nods his head. As soon as he completed a nod, golden showers of light enveloped the two of you.

"What just happened?", asked Dudley as he started panicking.

"Oh, that was the pact. Should you try to break the pact, you will die. Just for safekeeping"

Dudley then spoke no more and he walked out of your room. As he left, you were exhilarating with joy. Dudley is under your fingertips but first, you should fulfil the promise. However, that bumbling idiot has given you a loophole to exploit. Dudley wants her in any form. You can either make Aunt Petunia confused while Dudley is seducing her, or you can transfigure yourself as Petunia and suffer for a while as you wish that she should succumb to you before anyone else...