Disclaimer: I do not own supernatural, even if it would make me a very happy person. Sam, Dean, Castiel and other referenced works belong to Eric Kripke.

A/N: At the end of Citizen Fang, I just started writing. I wrote about the differences between Dean and Sam's attitudes and why those separations might exist and why Sam couldn't accept Benny, and why Martin died and how this might affect their relationship and this is what came of it. Also, this is from Dean's P.O.V. and all the Sam thinks, feels etc, is what Dean really thinks about his brother.

What did Dean do that caused everyone good in his life, to turn into monsters, to make them lose their sense of reason?

Dad did it when his mother was burned.

Sam did it when he was with Ruby.

Cas did it when he swallowed the Leviathans, to save the world, from the war in Heaven.

Dean's insights were rarely, if ever, taken into account when his loved ones acted.

They acted on vengeance; Dean acted on love and a sense of morality. Not that he'd ever admit it, not with his GED, can-do-attitude and devil-may-care rebellion.

How could Sam turn out so different? Maybe Dean hadn't taught him the unconditional love that he had for Sam. He would love Sam always, he's proved as much. Through the bratty, needy kid Sammy, to the angry rebellious teenaged Sammy, the Stanford era, the demon blood, through starting the apocalypse, soulless Sam, crazy Sam, and now the Sam that despised him, he loved him.

It was the sort of love that hurt, what he felt for Sam. It wasn't mutual. Dean knew it, just like how Dean knew that his father loved his brother more. What his father felt for Dean was guilt, and regret, he proved that much when he died for him.

Benny had killed Martin, and Dean couldn't blame him.

From what Elisabeth said, the killing had been just. Martin had crossed a line; he had threatened Benny's family.

Benny was from the old world, where family mattered. Family was loyal, family listened, and family forgave.

Dean liked to believe that family was the same. That family hadn't changed. That family would kill for and die for each other. He had, many times.

Benny was his brother.

Sam resented Dean for that, he knew. He resented that Dean could consider someone family who they hadn't grown up with, hadn't spent years fighting alongside. He didn't realize that in purgatory, trust was built up fast and lost just as fast. They had accumulated 20 years of hunting experience together in a single year. It was a fight that was always, 360 degrees of combat. Even with the apocalypse Sam and Dean had moments of peace. Benny, Dean, and Castiel's moments of peace were rare, he could count them on one hand, and lasted minutes at best. Benny had proved himself more loyal to Dean in that year, than Sammy had in a lifetime. Benny had his back, and Castiel's back also.

Sam now thought of Dean as an obligation, someone who had let go for a whole year, when he was in reach. Sam was with Dean for the same reason his dad had died for him… guilt.

Dean reminded Sam that he still had a debt to pay, that he had started the apocalypse, that he owed thousands of people their lives, for what he had done, just by being there.

Sam despised obligation, that's why he hated Dad so much. Unlike, Dean who had taken his obligations and built on them happily following orders, Sam wanted to live his life his way.

Dean reminded him, with his-battleworn,-hardly-slept-at-night-hunting-is-his-only-talent way of living that it wasn't up to him. He owed the world, and the world needed the compensation.

Dean had babied Sam, that's true. Dean had frequently gone without so Sammy could have what he wanted. Dean doesn't remember a time where he wasn't willing to share or sacrifice something for Sammy, including girls.

Dean remembered becoming a big brother, little Sammy home from the hospital just for him. He was told that Sammy was a very important gift, which he had to be careful with. Dean would sneak up to Sammy's crib, just to watch him sleep. His gift, the boy he imagined to always be with him, and be his friend.

Dean has learned, that Sam has seen him as responsibility, obligation and someone who gave him sustenance when needed. Dean was his Dad, not his friend, not his partner-in-crime, but someone who supported him physically and tried to control his path. Not his friend.

Dean, he's slowly becoming his own man. Before he was what his father wanted him to be, what Sammy needed him to be.

Now Dean looks to himself as a moral compass, his own experiences coloring the philosophy that he lives by, forever dynamic.

Sammy hates it. Sammy hates that he believes that with the knowledge that Dean and him have been given, that it's their duty to protect people. To protect the normal that they both crave.

Sam just wants to take it, and believes Dean will always stop him. Sam is biding his time, until they can stuff all the demons back into the desolate place they came from.

Dean is changing, and Sam can't see it. Sam still sees the man who was ready to follow without question, whose stubbornness brought him to die for Sammy and go to hell. He sees the man who believes that he's right, arrogant, and ready to lay down the law in black and white.

Sam believes in gray, and believes Dean always hasn't. Sam doesn't understand why Dean is okay with Benny when he goes against what he believes is Dean's foundational philosophies. What he believes Dean and John had tried to instill in him, growing up. The philosophy that he questioned when confronted by Amy Pond, a girl and monster who killed her mother so he could live.

That was when Sam learned that not all monsters are monsters. That is when Sam believed that he was different from his brother and father. His brother and father would have wanted him to kill Amy; after all, she was the monster they had been after.

Sam was going to kill Amy, misunderstanding the teachings of his father and older brother. The teachings that both his guardians had tried to protect him from. Perhaps that was the folly that led to Sam believing that he thought so differently from his family of world protectors. They tried to protect him from the truth of what was out there in the dark, and had allowed him to draw his own conclusions by himself about what was out there and about what his family did, how "normal" people lived.

John had tried to hide the truth of hunting from his youngest and Dean, had tried to protect Sam from knowing how the "civilians" lived by schooling Sam in his ways.

He tried to teach him how to hustle pool, how to pick up a one night stand, how to make the time you're in town count and how to live on the road. Dean had tried to be his entire family wrapped up into one, he initially tried to create the life that their mother had given Dean… Dean soon learned that it was better to talk about their superhero Dad, when Sam was complaining about moving around all the time. It was better to talk about the benefits of always being on the road, no needy girls, if you're unpopular you won't be there for long, and what do grades matter when you're saving the world from the evil they don't even know?

He couldn't have known that he was instilling the ideas in Sam's head that his family lived for killing monsters, not for saving people, that only family was important and it was impossible that being normal and being part of the family was an impossibility.

So yeah, Dean supposed that they had some misunderstandings that were growing more obvious. That Dean killed Amy in part, because he couldn't even trust his best friend whom he had lost just before due to him doing what he believed that he was doing the right thing. If Dean couldn't trust the man who fell for him to stop the apocalypse how could he trust a woman who was programmed biologically to kill people and sustain herself and her son on a diet of human pituitary glands? Who proved that she would kill for her family, who was deciding who should die for her to save her son?

Dean couldn't trust anyone at that point. Sam didn't know how far Cas's betrayal had actually affected Dean.

Dean wasn't able to forgive Castiel fully until Purgatory, and that was when Dean learned to trust again. Dean trusted Benny. Dean and Benny knew each other's motivations and Dean was Benny's lifeline on keeping straight.

So yeah, he killed a soccer mom because she was killing people and he couldn't trust that she wouldn't do it again like she claimed, he couldn't trust his brother's judgment who had recently gone insane, and he sure has hell wasn't ready to trust a monster after getting burned by an angel, and his former business partner in the apocalypse. It was a world where he couldn't trust pie, or anything else with high fructose corn syrup thanks to his angel.

So he killed her, and regretted it instantly. He hated himself when he saw her son, and realized what he had taken from the kid, the complete innocent. He had promised himself when he started hunting on his own that he would do his best to allow innocents to go about their lives without the supernatural negatively affecting him. He realized that he had done the same to that kid that the yellow-eyed demon had done to him. He hoped that one day that kid got his justice, because he knew he deserved it.

He felt that perhaps this mother was telling the truth when she swore she'd never do it again. That maybe, it wasn't his right to decide if she was telling the truth. So he regretted killing Amy Pond for much more than the rift it created between him and his baby brother Sam.

He grew from it, and when his daughter Emma, came to kill him, he was ready to take his punishment if she saw it fit to kill him. He was ready to welcome her into his arms too, if she wasn't ready. Sam had taken away his chance at penance, or his chance at a family, and his chance to find out which she would decide.

So when Dean met a monster that proved he could trust him, he wasn't going to half-ass it, he knew Benny, and he knew Benny's heart.

Benny had killed for his family, and Martin in his quick judgment, had paid the price.

Sam could jump to conclusions if he wanted to. Dean sure as hell couldn't fault Benny for what he did to Martin. He thought it a shame that Martin had been out of the crazy house for so little and was already dead.

At least he knew he'd go to heaven, even if it was another person who died blaming the Winchesters for his death.

Dean's insights should be heeded. He lived and breathed hunting, it created the person who he is, and was his talent. He wasn't slow, his focus was just elsewhere. It laid solely on people and how to save him. Dean knew Benny was a good guy, on the path to rehabilitation just like Dean, Castiel, or Sam. They had all done things that they regretted but were now making up for it. Paying penance like Castiel had said.

Dean was right about Benny. Even if that meant Sam was wrong about Dean. Even if that meant that Dean and Sam couldn't get along anymore.

He was not messing it up again by killing an innocent person again, like Amy.

Sam be damned.

A/N: I'd like to hear others' views on why Sam and Dean ended up so different. So review or pm me if you'd like to talk about it. Most especially if you think I'm completely off base.