Vallery has heard about what you did to your aunt during school break. No need to deny it Harry. You using magic on a muggle in such a BIG way was in all of the papers and Vallery thinks you need to be taught a lesson. The only way to make it right, is to us a spell for a spell. She admits she loves fat guys and using the same rapid expansion spell of you will bring her a lot of enjoyment. Only difference with her spell is that instead of blowing you up with air, she is going to be expanding you by working magic on your fat cells. That's right. You are about to get real fat, real fast Harry and all for Val's own enjoyment.