One: She was three years older then him.
He fell for her first day of school, that long blond hair, that bright smile...that amazing body.
Sam thought he was in love. Only Dean realized she was just leading him on to make her other potional lovers jealous.
So when Dean 'broke them up' Sam pouted for days. Refused to hunt, refused to even accept his brother's apology. Dean couldn't have helped but feel it might have been better if Sam had just gone through it.
At lest he wouldn't have been mad at him.
Two: Dad. Sam. Standford.
It was a recipe for chaos.
And when it mixed Dean's world blew to pieces. He stood on the side lines as long as he could, watching while his heart broke as the two people he loved most hurt each other.
It was when his father lifted his fist to hit Sam when Dean stepped it.
He blocked his father's fist then ultimately let him go. Because that was what was best for him...didn't matter that Dean felt like he'd just lost a part of his soul.
Three:It was after Jess. A.J pretty much how Dean thought of his life now.
He knew full well that his brother wasn't there for him...wasn't with him because he saw that family was more important.
He was with his big brother because he had no where else to be.
So when Sam got scared, buried his face into his neck, wrapped his arms around his body and pleaded for something Dean had dreamed about, he refused. Instead he calmed him down, put him to sleep and cried in the bathroom.
Sam always came first, no matter how much he regretted it.
