Dean and Sam Winchester have always loved each other, just not the way brothers are supposed to feel about each other. Dean has always loved Sam since he first laid eyes on him, but I'm getting ahead of myself. Lets start from the begininng, when Sam was born.
It was May 2nd, 1983 in Lawrence Kansas when Sam was born. Mary Winchester was giving birth and John didn't even think about telling his 4 year old son, Dean, to leave the room. Dean watched his mother going through agony while she was giving birth to his little brother. He watched Sam being birthed and didn't feel anything. He didn't know why he didn't feel like he was going to throw up or pass out while his father was out cold on the floor.
The Doctor gave the little boy ready to be named to his mother. She took him in her arms and named him, Samuel Winchester. She gave Sam to Dean and when Dean had looked down at Sam he promised to himself that he were to love and protect Sam until the day he died.
-Six Months Later-
Dean woke up to screaming coming from his brothers room. He ran down the hall as fast as he could but was stopped by his dad right outside Sam's door. He could see flames in his little brothers room and he was scared for his little brothers life. He looked up and saw his mother on the ceiling with a gigantic cut on her stomach and flames all around her.
His father John was at the door way with Sam in his hands and he gave Sam to Dean sreaming to take Sam to safety outside. His father stayed inside the best he could before he had to leave. After Dean and John found out that Mary was dead, it changed them. John turned into a unstopable killing machine to kill whoever killed his wife. He engrossed himself in killing mythical creatures and logging them into his journal.
He was harder on Dean and Dean had to start creating a harder shell around him to protect him and his brother. He started looking after his brother since his dad was either on a mission or drunk at the bar closest to the hotel that they were presently staying at. John was never mean to Sam, He would hit Dean from time to time but never laid a finger on Sam.
Dean was John's punching bag and Sam comforted Dean after he was hit. John always had enough money because he would sell his body out for money and would force Dean to be raped. He would rape Dean occasionly himself and then punch Dean repeatedly.
Dean took care of Sam as if Sam was his own son. He was a mother, brother, and father to Sam. John was out on a mission trying to kill a witch doctor. Sam was about 2 years old at the time. Sam had looked up at Dean and said Dee. He couldn't say Dean at the time and that was Dean's nickname for the rest of thir lives. Dean was so proud he sat there and cried while Sam tried to comfort him thinking that something was wrong.