Why did the creature want justine to suffer and how did he decide to accomplish that?

The creature wanted Justine to suffer because he knew that when Justine woke up and saw him, she would reject him just as others have. He had nobody to love him and he was sad and lonely. She personified all that he could not have. He decided to punish Justine by framing her for the killing of William. He placed the portrait of Caroline in Justine's dress so that she would be the one accused of murdering William.