In Friday the 13th (2009), Jason Voorhees encounters a group of young campers. In usual Jason Voorhees style, he kills them instantly without a second thought. Two campers (Whitney and her boyfriend) stumble upon his house in the woods where Jason discovers their presence. Jason promptly kills Whitney's boyfriend, but ends up holding Whitney as his prisoner for approximately 6 weeks.
Jason Voorhees has never held one of his victims captive in any of the previous films (to my knowledge). Why did he chose to keep Whitney as a prisoner instead of just killing her like he usually does? Is there any explanation from filmmakers as to why Whitney was a prisoner rather than just another murder victim?