Father
As a teen, Sam hated it when Dean would tell him, "You and Dad are so much alike." The last thing Samuel Winchester wanted was to be anything like his father. There were times when Sam was positive John didn't care about his sons. He dragged them across the country hunting monsters for cryin' out loud! What kind of father does that?
It took his dad's death for things to begin making sense.
He was preparing his sons, teaching them how to protect themselves from evil.
Looking back, Sam took "You and Dad are so much alike," as a compliment.