If you've read 'Forgiveness, I can't imagine...' then you know that John, is a piece of sh*t. In the book, its explained very vague why. Because behind every villain is a person. But then again, John isn't the villain of this story. So read this prequel and discover why John may not be the person that he displays.
'Because we all have a reason to do certain things'
Stiles can't sleep, and if he told enough people that was all it was, maybe he would start to believe it. Still, as tensions were rising about them losing their territory he couldn't bother them with something he didn't even fully understand. Maybe he just needed something fun and easy to help him relax. Like the hot neighbor that he keeps catching staring at him.
Derek can't sleep, and if he cleans his house enough maybe people won't realize how he doesn't care enough to clean up other parts of his life. Still, as he worried about his job and obligations, he couldn't let them down about finding a place they belonged. Maybe he just needed something interesting to keep his mind off of it. Like the clumsy man he can't keep his eyes off of.