your father was having trouble building a house. It bothered him so much and with his OCD, it killed him. He started to kill people, and that's when his OCD... disappeared. He came home with blood on himself as you were in the kitchen. He walked up to you, and spoke

"You're gonna help me... I need your eyes.."

he dragged you to the freezer downtown, and opened the door, and exposed you to... a house of bodies... you were shocked and went to vomit in the corner. He knew you'd react that way... he drove you home. The next morning, he woke you up, and brought you with him to kill... he needed you to see and understand why he does it...