Dean always thought that his fellow angels were going about the humans the wrong way. The angels were always calling them apes and other derogatory terms, and Dean did not agree with that. He was more inclined to think of the humans as family.
Castiel, Samuel, and him had been speaking of this since the birth of the humans. Castiel and Samuel had been on Dean's side from the beginning. Together they would joke about about how all of heaven was acting. Their ongoing joke was that one day Samuel, Dean, and Castiel would rebel from heaven and live a human life. They never thought it would actually happen.
Samuel and Castiel were the rule followers of heaven and now one of the had rebelled and the other was teetering on the edge of disobedience. Dean was in a panic, and could not believe that his brothers would do such a thing. He felt betrayed when Castiel rebelled. Dean would never do something like that. He could not imagine betraying his family.
Dean gazed at Samuel in disbelief, "How could you possibly betray me too, Samuel? I thought you were better than that disgrace Castiel!" Dean could see how much these words hurt Samuel. Samuel's face remained composed at all time of day and night, but after these words that cut the air were spoken his composure fell. He was on the verge of tearing up. He had never been called a disgrace by anyone.
"Dean, Castiel has told me how bad the humans live are. Like you said they are family too. We need to help them, and does it look like anyone else is going to step up?"
"Wait. Castiel has been up here to talk to you? Do you guys even know how far off the reservation you have gone?" Dean said with a mixture of feelings: most of the hatred was directed at Castiel for daring to show his face in heaven, and disappointment for not including Dean in the discussion.
Yes, I have been talking to Castiel here. Hold on." Samuel said while raising an arm to stop Dean from interjecting. "Castiel wanted to include you in our talks, but I advised him against it." Dean had taken a step back and was now listening quietly. "Dean... We...I knew how you would react to seeing his face after he rebelled. After he left you here."
Dean turned around to hide his face. The conversation put Samuel in the same boat as Castiel. He had never felt so conflicted in his extremely long life. He always used to follow the rules that were set for him without question, and now he was thinking about rebelling along with Samuel and Castiel. He was appalled that the thought crossed his mind. "Just get out Samuel." Dean said, the tone of his voice sharing how tired he really was.
Dean turned back around to find that Samuel had in fact gone. He was alone. How could they do this to me? Dean's mind was screaming with the enormity of his brothers rebelling. He had walked in on his favorite heaven. There was a family eating a great dinner, and everyone was laughing and having the time of their lives. He wanted that reality to become his own. Was happiness really too much to ask for?
Seeing this family he realized that Castiel and Samuel were the only angels that he enjoyed taking to. They were the only ones that did not think of the humans as trash.
The choice had presented itself suddenly, and so too his answer came. He was going to rebel. He was tired of all the other angels being disappointed in him and his favorite brothers. He was tired of his violent, childish siblings using Castiel and Samuel as punching bags Dean wanted them to be heroes, and he knew they were capable of that and more, but the only way for that to happen would be for him to help them out.