Winter's Revenge.

Experiment 497, who likes to be called Winter, Grew up in a Lab, she had seen almost everything, or at least she thought she had. After the scientists at the Lab she calls Home kill her little sister on "Accident" she takes matters into her own hands, along with her brother, Experiment 498, Justin-Experiment 501 and Cheyenne-Experiment 500, she escapes. When she finds out there are more kids like her and her friends they all discover they are all shifters. So is everyone in their world. Even in that case she is different, they all are. And for Winter, Revenge is ALWAYS the answer... As the aniversary of her little sister's death comes about she decides it's time to pay her old Home a visit.