An appropriation might include seeing Goldilocks as a thief, which she essentially is. She breaks and enters, steals food, cases the house, and gets caught in the act, but is able to escape. So appropriate the characters and the storyline and challenge the fair and innocent version of Goldilocks that many have come to know. Craft her as smart and deceptive, using her looks, abusing the misconception that she is innocent and "just didn't know." Rather, she knows very well what she is doing, where she it at, whom she is about to ripoff, which is a family of three, who have a child, who are looking out for the welfare of their kid. 

And you need to consider Campbell's hero's journey: the calling (how does Goldilocks start her journey or here of this place she can get into and thieve); the crossing the threshold into an unknown world (the bears' home); the tasks and trials within the quest (things she must overcome and accomplish); a return home (which, maybe in your version, she doesn't, thwarting conventional fairy tale endings; and she is put on public trial). 

Or, to completely alter convention, come at your appropriation from the Bears' point of view, who are going to lure this thief into their home, because this has happened to them one too many times before. And it's finally an attempt to put a stop to this blonde nuisance.