It was the crippling sense of guilt that did it. Because, as we know, literally everything bad that happens in Beacon Hills is Derek's fault. He probably killed your mom, Stiles. While starting World War II. Maybe causing an oil spill too.

Damn it, Derek.

"You don't want to be alone. Trust me," he muttered, attempting to set the couch on fire with the power of his glare. Because that was Derek's thing. Soul crushing loneliness was his thing.