This time last year, rumblings in the fandom over Dean's supposed lack of character development got me in a tizzy, so I wrote an article, "A Deeper Look at Season Three Dean Winchester" for blogcritics in response to that misconception.  I eventually followed it up with one about Sam and they got some discussion going.  This year, all the rumblings seem to be over Sam's character, so I've decided to do a similiar analysis for season four and start with Sam.  There's a lot more to look at this year.  I guess a full 22 episode season will do that! 

So, get your meta hats on everyone and enjoy (or feel compelled to totally rip apart) "A Deeper Look At Season Four Sam Winchester." 

No doubt, in terms of the calendar frame for season four, Sam Winchester had one really bad year. His brother dies, he tries to unsuccessfully get him back while taking up a bad drinking habit, he starts down a dark road he fought all those years to avoid, his brother miraculously comes back but they fight, he carries on his pursuit of revenge behind his brother's back and gets hooked on demon blood in the process, he spirals out of control and turns into the monster he never wanted to be, he tries to kill said brother after a forced detox goes wrong, and...oh yeah, he inadvertently starts the apocalypse. Not good.
I really don't understand the complaints about Sam's lack of character development in season four. He had TONS of character development. Sure, he nosedived into something unrecognizable by the end, but I believe that is the point. While it's sad, ultimately all heroes have to face bitter lows before they reach new highs. Anyone who watches TV, films and/or reads comics knows those are the rules.
Let's go through a few of the key Sam episodes and take a good honest look at just how much his character did change. It's massive and quite compelling when looking at it through a microscope.
There's way more to this episode than meets the eye. As we learn from "Lazarus Rising," Sam has been honing in on his pulling-demons-from-humans-with-his-mind trick.   Obviously in the back of his mind, there's that little fear that he's going to lose control and go dark. And get caught by Dean. Which he totally does in this episode.  At this stage, he's lying to himself, mostly to quell that nagging voice within that's telling him what he's doing is wrong. Statements like "I won't let it get too far" and "You have a choice" support that.
So, what happens when that nagging voice becomes your absolutely livid brother yelling at you? And tossing lamps across the room? Treating you like that freak you don't want to be? Sam withdraws, but Dean's constant belittling pushes him into a long overdue outburst. He comes clean with Dean. "I've got demon blood in me Dean! This disease pumping through my veins and I can't ever rip it out and scrub it clean. I'm a whole new level of freak! And I'm just trying to take this curse and make something good out of it, because I have to."
Dean settles down and agrees to try Sam's way, probably because he knows when he gets an outburst like that from Sam, he means it. Sam so wants Jack to overcome his natural tendency to change into something non-human. Just with previous episodes like "Heart," saving the monster of the week means there's hope for him. Just like with "Heart" though, it ends badly and Sam's hope is crushed. He can't share his burden with Dean though, for Dean would never understand. Only someone with a monster inside would. Like the monster he just killed.
The ending scene shows a departure for Sam from the past. Sam has let Dean always call the shots and his big brother's approval meant more to him than anything. Here, he decides to stop using his abilities for his reasons. "Don't thank me. I'm not doing this for you. Or for the angels. This is my choice." That's something he's only mildly proclaimed before this, like in "Time Is On My Side." He's clearly learned to get on without Dean, while Dean wants to go back to the way things were. 
This is also the early sign of an issue that gradually builds over the season. Sam desperately wishes Dean would trust him and let him follow his own path. When Dean doesn't give him that show of faith, Sam withdraws and becomes closer to Ruby, who gives him that desperate desire for approval. No wonder she's able to manipulate Sam, she gives him the one thing he never got from anyone else in his life. Acceptance for what he is.
It's The Great Pumpkin Sam Winchester
This episode broke my heart for poor Sam. Despite all the horrors in his life, he still had a shred of faith. One has to wonder if that shred was what kept him going all this time. His first encounter with angels, especially the brutal Uriel, all but decimated that remaining shred. Also, the reality hit that he couldn't stop using his powers if he needed them to save himself, Dean, and the world. He goes against Dean's and the angels' wishes because there is a bigger picture involved. The sad truth now is there's no going back.

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This episode knocked him down enough where from this point forward, he became prone to doing exactly what he didn't want to do for the sake of the greater good. He couldn't rely anyone or anything anymore, even Dean. He could only follow his path based on his instincts and his good intentions.
Wishful Thinking
I bring up this one for only that one scene at the wishing well. When presented the opportunity to wish the life he always wanted, Sam admits "I'm not that guy anymore." His deepest desire is one of single focus, "Lilith's head on a plate, bloody." That obssessive mindset wreaks of John Winchester, and accents for us the very wrong path Sam is headed.

I Know What You Did Last Summer
I don't get why this episode is so misunderstood. As I've said before, it's gorgeous. Anyone who said this was the "Saint Ruby" hour wasn't watching the same episode I was. I paid careful attention to Sam and let everything else become background noise. 

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Sam's devastation over Dean's death is groundshaking. He is very, very broken. Jared plays that beautifully! The emotional spectrum that Sam wavers between is literally taller than the man himself. His confrontation with the Crossroads demon shows Sam at his last raw nerve. He's in so much pain he doesn't want to live anymore. The next scene proves it too when he dares Ruby to kill him.
Sam is hurting so bad he without hestiation does the one thing he and Dean never wanted him to do, use his powers. That again kicks in Sam's instinct to spite himself when hope is lost. He couldn't save Dean, he might as well become that monster. The worst thing that could happen is that he dies, the best is that he saves people. He had that mentality about Jess in season one too. He'd rather die in the name of revenge (or justice in his mind) than deal with the pain alone.
So what's a person at the total bottom going to do? Cave into a moment of intense weakness, that's what. When Sam gives into Ruby's advances, he's in deep pain both physically (headaches from demon pulling) and emotionally. He needs something to take that pain away, right or wrong. A brutally desperate man will do the worst possible things, like sleep with a demon.
Ruby had to be there for him. Despite what we like to think. Sam wasn't (and still might not be) in a place to pull things together on his own. He would have destroyed himself. That wouldn't have made a good show.
Criss Angel Is A Douchebag/After School Special
I put these two together for a reason, other than both are Sam centric. I still debate whether they aired in the proper order. I'm wondering if the "You happy Sam?" would have made his decision at the end of Criss Angel all that more powerful. 
In Criss Angel, Ruby decides its button pushing time. Sam needs less time to do cases with Dean and more time with her hunting Lilith. She begs him to do "that" but Sam has a huge problem with "that." Sam's determined to make this his decision though, thus making a great tie back to Metamorphosis. 
He asks Dean if he thinks they're gonna do this when they're old. Dean bluntly tells him they'll be dead (for real) before then. If they do live, they'll become Bobby, who hasn't exactly grown old gracefully. Sam sees the tragic tale of the three aging magicians and even though he doesn't want to do it, he's going with Ruby's plan. "I don't want to be doing this when I'm old," aka, he's ready to sacrfice himself for the greater good.
Of course no sooner than he makes that choice, he gets to revisit a place that gave him one of his few positive experiences in his life. He gets to see again his old teacher, who when he was 14 told him he had choices in life, that he didn't have to go into the family business.  Sam came across as self actualized in this one, even giving that life goes on speech to the ghost of his former classmate, but all that unraveled at the very end. All that confidence, all that pride, fell apart with that one question. That's when he realizes he doesn't have control of his destiny. He is never going to be normal. Remember this, for it comes into play later.
So which ending was better to come first? I could see the answer going both ways. No matter which way, Sam is setting himself up for a fall.
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Sex And Violence
So, just like the doctor that seduces him, is it possible Sam is living like there's no tomorrow? The stakes are getting higher now, and he's gotta step up. He schemes with Ruby behind Dean's back, who's crushed when he figures it out. Then he has the one night stand with the lively doctor, something that's a bit out of character for him (Dean even points that out in the end). Maybe it all means he has nothing to lose?
The siren's spell obviously has the most interesting impact. Spell or not, Dean is pretty hurt by Sam's actions even before they say those awful words to each other. Sam just makes it worse. At the end Sam's mortified by his words and actions in trying to harm Dean, but won't apologize or discuss his sneaking around with Ruby. He uses the siren spell as an excuse to brush everything under the rug. "So, we're cool?" They are so not cool. 

Death Takes A Holiday
Dean is still holding onto the feelings of betrayal, but Sam won't discuss his actions. He's still on the siren spell excuse. His powers are really amping up, so much so he can now do the TK toss! We see it in his eyes, he likes having that power. He likes dishing it out to baddies like Alastair after all the harm they've done. He's transforming, but still keeping Dean in the dark.
However, this is also where we start seeing signs of Sam losing control. He's still lying to himself, and sees nothing wrong with his actions until a dying Pamela tells him to think again. She felt that evil inside him. She knows. Sam is obviously alarmed by this, but not enough to stop now. He's gone too far.
On The Head Of A Pin
This is where Sam starts seeking personal justification for his actions, especially after Pamela's jarring words. He goes to Ruby for help after Dean is taken by the angels, acknowledging what he's doing is wrong, but justifies everything because Dean isn't strong enough and needs him. Now the big reveal, he's drinking demon blood! Ew, yuck, so wrong. That boy's gonna crash hard.
Still, he becomes powerful enough now to zap Alastair's soul into dust, saving Castiel in the process. We see how much Sam is hooked on that power now, but Castiel's unsettled expression is enough to tell us something isn't right.  

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The Monster At The End Of This Book
Sam's in too deep now. Thanks to Chuck The Prophet, who has seen everything Sam is doing, Sam finally finds someone to share his burdens and his fears with. Chuck won't put Sam's demon blood drinking in the books, for he doesn't want Sam to look unsympathetic. "You have to know what you're doing is wrong." Sam knows, but he can't stop. He justifies that he must kill Lilith and stop the apocalypse. Chuck points out that's Dean's job, but Sam is now more convinced Dean isn't strong enough. He wants to finally look out for Dean the way Dean has for him his whole life. That's the sure fire sign he's completely lost control.
Sam is itching to confront Lilith, and their little encounter only makes him more eager for revenge at the end. We can speculate that's why Lilith came to see him, to rile him up enough where he'll continue with the demon blood. No matter what her reason's, Sam is in a bad place.

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Jump The Shark
The Sam scariness continues, this time as he morphs into the carbon copy of John Winchester. When that development even chills Dean, you know its not good.
So, when the notion of a third Winchester brother came along, was it shocking that Sam took the cold militaristic stance and decided to treat Adam as more of a soldier than a brother? Yes and no. It's shocking in a sense that Sam resented his dad for treating him that way most of his life, but does the same here. It's also not shocking because Sam's new found "practicality" has pushed him into being that cold and harsh. It's all about survival, they are at war. 
In the end, Sam's behavior is just plain unsettling. His single minded focus for revenge blinds him to the truth, that Adam isn't who he said he is. That also becomes perfect foreshadowing for Sam's outcomes in the final few episodes. Luckily Dean is able to get past the brother thing enough to work the case and ultimately save Sam.
The Rapture
Uh oh, we've got a strung out junkie on our hands. His intense bleeding from "Jump The Shark" no doubt left Sam a little dry and his "dealer" is MIA. Sam can't even exorcise stunt demon #3. Dean is worried, but Sam is outright disturbed. I smell a fall coming.
Uh, yeah, cutting and sucking blood from a demon during a fight in which your brother and his angel pal are watching is not a wise move. Cat's out of the bag now. Sam still thinks though that all Dean will do is yell at him and it'll all be better. Dean doesn't yell though, yet Sam still lulls himself into a false sense of security. Word of advice to all junkies out there, don't walk into a panic room first when your brother is quietly upset with you. It's intervention time!

When The Levee Breaks
I could devote an entire article to Sam's crumbling psyche here. As a matter of fact, I already did in my episode review. This is the episode where I feel I finally got to know what happens in Sam's mind. Let's summarize some of the inner fears that he wrestled with:
- Fear of torture. Who doesn't have that? It's a very real primal emotion, so why not get that one out of the way first?   That could also be Sam's mind putting into a physical form the mental torture he constantly puts himself through, but I think I'm stretching.

- Fear of failure. Basically, he abandoned all his hopes and dreams for a better life. It still tears him apart, thus getting berated by his 14 year old self. That shows that subconsciously Sam still desperately wants to be normal, even though he's choosing not to for the greater good.
- Fear of isolation. Sam desperately wants someone who's close to him to understand who he is and be proud. That can only come from Dean, and Dean showed the ultimate lack of faith by locking him in the panic room to begin with. So his hallucinatory mind goes to the one family member that never alienated him, his mother. She tells him everything he needs to hear. She's proud and he has to make those rough choices. "Even if it kills me?" He asks. He finally can share with someone how the evil inside is consuming him and how much what he's doing scares him. She knows, she understands, she supports and encourages him, and even strokes him in comfort, which is what a good mother does for her boy. Then it all disappears, for it isn't real. My heart was crushed over that. When Ruby tries the same thing later, he won't accept it. It's not the same.

- Fear of rejection. Sam's most intense fear comes from a confrontational Dean, who berates him for being a monster. Sam, chained to the bed, could only listen in heartbreak. As soon as he escapes and hooks up with Ruby, he is very hurt over what Dean did to him, but still wanted to make things right. Since that last horrible confrontation was a hallucination, surely he could still reason with Dean. 
Unfortunately, what he got is the worst thing possible. Despite Sam's heartfelt plea to Dean to trust him, Dean to his face calls him a monster, the absolute one thing he couldn't bear to hear. He would have to face his fate and die alone now. I found it really interesting that instead of angrily walking away, Sam reacts by punching Dean. The demon blood has made him unstable.
Naturally Dean punches back, but to see all that pent up rage take over Sam so much that he almost strangles to death his injured brother is a massive character defining moment. Sure, Sam's a little unbalanced right now, but he no longer needs big brother's approval. He'll carry on without him. Oh, the parting words though hurt, at least for a fan. "You don't know me. You never will." There's no way Sam is going to take to heart Dean's ultimatum not to leave. The damage is already done.

Lucifer Rising
Ultimately, without Dean's support, Sam resigns himself to becoming the monster he was always meant to be. He focuses on the one and most important goal, killing Lilith. Not having Dean in his corner takes its toll though, for Sam has regrets. Maybe he can't do this on his own. Maybe he isn't doing the right thing.  He questions until he gets the final blow, the tampered with voice mail in which Dean calls him a blood sucking Vampire, as well as a monster. That's all he needs. Killing Lilith is all that matters and he's ready to die. There he goes spiting himself again.
Of course Ruby's manipulation changes all that, and not only is Sam shattered by the result, now the world is too. That's where season five begins. Sam is in the worst possible place right now. Sam's only options at this point are redemption, insanity, or death. Guess which one I'm rooting for?

Coming soon, a deeper look at Dean through season four. His tale is a little more uplifting.