Claim her body as your own

The amulet glows a deep red as an almost... Menacing grin slides across your face, your sister's eyes going wide as you toss her hair back.

"Sorry, sis... Can't have you running off to warn people..."

You cup her... No, your breasts as you stretch, bouncing them lightly as you coo at the feelings...

'No... No, get out!'

Her mind was weak from the intrusion, your powers having been bolstered by hers... It didn't take much before her mind goes limp, yours sinking inside the hollow husk that used to be her will... You were her now, mind, body and soul. You felt like nothing could stop you as you begin to ponder on what you could do with your new found powers... She had been planning on taking over the family with the amulet... It sounded like a good idea, actually... But this was still your sister's body, perhaps it could use a few more... Personal touches to finalize exactly who the new owner was.