Part one can be found here: 

http://www.thewinchesterfamilybusiness.com/articles/36-sam-winchester/6591-the-enigma-and-cruelty-of-sams-winchesters-powers-part-one.html

Part Two

“How sure are you that what you brought back is one hundred percent Sam?”  (Azazel, “All Hell Breaks Loose”)
 
 

Wherever Sam was, it did change him. The man who returned from the grave was a different one. Not blatantly visible, but his reactions changed. He killed Jake in cold blood. He grew less sensitive when it came to destroying demons or using them – as he intended to do with Ruby, in order to save Dean from hell.

The impending fate of his brother served as a path to Sam’s development into a more Dean-like type, but the catalyst to be able to do that must have been his time in death (allow me to put it that way, as we have no idea where he was, what he experienced – I hope to have the chance to ask that at the Con in March, that question has been bugging me for a long time now).  

Ruby pushed all the right buttons. She dangled the possibility of saving Dean in front of Sam like sweet meat on a hook. She eventually made him believe that he was able to actually help Dean, but still it took Sam to be desperate enough to even consider to use whatever was in him (shortly before Dean’s time was up and they had not found a way to free him from his deal). Even though Sam began to change, he had to believe in what he had always believed. And he must have felt on the safe side (at least for a while) since his powers were gone ‘ever since YellowEyes died’ – ‘not gone. Dormant.’ Ruby pointed out.

At least for the third season Sam got a break from visions assaulting him in dreams or in the street and those horrific headaches. But, of course, this is Supernatural, he was not at ease at all. He tried and tried to save his brother from his deal, he even considered alchemy, thereby risking to turn Dean into a creature that would slowly cease to be entirely human – when the first organ would need to be replaced, at the latest, which would transform Dean into some kind of Frankenstein’s monster, respectably Winchester’s monster.

Sam knew how absurd this idea was, but the fear of having to live without his brother (and probably of the building amount of guilt, as Dean would die because of him) was too devastating. There was another aspect that added to Sam’s guilt account: in Bedtime Stories he went after the Crossroads Demon to force her to release Dean (unbeknownst to him, she did not hold the contract), and she rubbed a sombre truth in: ‘You’re here, going through the motions, but truth is, you’ll be a tiny bit relieved when he’s gone. … No more desperate, sloppy, needy Dean. You can finally be free.’ 

She had a point. In the state of mind Sam was in he was too angry (and probably too shocked) to even consider whether she might be right, but later he would tell Dean that one of the reasons why he went off with Ruby was to get away from his brother, because Dean would not let him grow up.  Trying to save Dean was an act of love – he didn’t want his brother to die – but also an act of autonomy: the roles would be reversed. Sam would be a stronger part in their relationship. He would be able to meet Dean as his equal, in his older brother’s eyes; so far Sam was still the baby brother. Unfortunately, that did not work out. Dean refused to fall back on so desperate a measure that would involve risking Sam’s soul which was tantamount to trying to tap whatever powers were hiding in Sam. And – it was also too late to start any training.   ‘

It’s gonna get darker and darker, and God knows where it ends.’
(Dean, "Metamorphosis")  

Dean died at the claws and teeth of hellhounds, while Sam was forced to watch, unexpectedly immune to ‘demon ray gun stuff’, the horrific picture lodged in his brain like a bullet – and all of a sudden he was alone. He distanced himself from everyone, even Bobby.  

He was terrified, lonely, angry, desperate – in the darkest place he had ever been. He was squatting in some old, dilapidated house, surrounded by garbage, and one might wonder when the last time was he actually showered. He lived on fast food (we’ve seen pizza boxes on table and floor) which was most unusual for the guy who had always eaten healthily. And he drank a lot. Actually, Sam was pretty much drunk for most of the time. Unable to accept the fact of Dean rotting in hell, he ‘tried everything. … I tried opening the Devil’s Gate. Hell, I tried to bargain, but not demon would deal.’  

He tried out – probably various – crossroads, killing the demon employed there along the way, and when Ruby found him he was downright suicidal. He was not only in mourning, he was depressed and forlorn and he didn’t care much for his own life. He went on path revenge, but, as we have learned in "I Know What You Did Last Summer," he was ready to die when trapped by demons. Scared, but ready.  

In a moment Sam had reached the end of his road, he found something that helped him go on: Ruby gave him compassion, warmth, a goal to fight for (take revenge on Lilith), desperate, at times violent sex, she cared for him, saved his life more than once, found the words to get through to him, acted like a protective sister – and, of course, she taught him how to use his powers and enhanced them with blood (well, she made him believe that he needed the blood, not telling him that he had it in him the whole time). And she gave him a new purpose, as his life was empty: get ‘Lilith’s head on a plate. Bloody.’  

But he was ‘a crappy student’. He didn’t pick up on exorcising right away, he paid with bad headaches for it, and his nose did bleed from the exertion. I suppose the first time Sam actually managed to get it right was the moment Ruby was in danger, and he took out the demon about to kill her. Again, under duress, his power emerged like a punch (not unlike the cabinet-moment) – he had to save her, as she provided the only stability he found during that time, so he did, and what had begun as some kind of telekinetic premonition asset turned into Jedi force. The dark kind.

    

I’m not saying she took the place of Dean, but she became an ally he needed – and, of course, she knew how to kill Lilith.  She did not tell Sam, though, why Lilith had to die.  

It’s safe to assume, that Sam was ashamed of what he was doing. The moment Dean came back, the lying began. Ruby, who opened the door to Sam and Bobby, was discarded as some bed-fun chick, to keep their secret safe. Repeatedly Sam stole away to train and to do what he had done best after he had picked up on exorcising with his mind, saving the victim.  

Sucking blood was wrong, he knew that, and he probably grew more ashamed about it as he began to realize how addictive demon juice was. So, in order to be able to live with himself (apart from his wish to strike Lilith) he needed to do something right.  

Shame, as I found often, is probably one of the strongest emotions around. It serves as an impenetrable wall behind which thoughts, interests, abilities, preferences, etc. are hidden from others’ eyes. It is held together by the fear of being humiliated, and eventually the fear of losing someone dear – when the ‘secret’ gets out, will the people closest to us be able to handle it? Or will they turn away? What will they think? Will they look at us differently? Will they treat us differently? It takes a huge amount of trust to be able to voice something we’re ashamed of. And judging from Dean’s harsh reactions concerning Sam’s Jedi mind tricks, Sam must have thought it too risky to open up.  

He knew now for sure that he was a freak, though he still fought to be normal in the deepest ravines of his soul. Not only had Azazel bled into his mouth and given him downstairs’ mothers’ milk, furthermore Sam did so himself – he had gone far already. And judging from the fear and rage constantly enveloping him he might have already thought that he was going too far. But he saw no other choice: ‘I’ve got demon blood in me, Dean. This disease pumping through my veins and I can’t ever rip it out or scrub it clean. I’m a whole new level of freak. And I’m trying to take this… this curse… and make something good out of it. Because I have to.’ ("Metamorphosis").  

The encounter with the rougarou however shook him. Sam tried to step back, do decide not to play with fire anymore, as the powers grew more seductive. And for a while he managed to stick to that resolution. He needed to believe, scared as he was, that everyone, no matter how huge the monster might be they kept inside, was able to choose. Free will. He had hoped so for Montgomery before he gave in to that urge inside of his, and Sam hoped for himself.  

Furthermore – the angels had warned him to cease his ‘extracurricular activities’. This came as a blow to the devout believer Sam had always been. Angels were real, and that obviously gave him hope. His prayers might have actually been heard. There was a greater power, a greater good watching (really?). So, there was hope – that is before he learned that the angels were not exactly the trustworthy kind.  

‘I thought they’d be different. I mean, I thought they’d be righteous. … This is God and Heaven? This is what I’ve been praying to?’ ("It’s The Great Pumpkin Sam Winchester")  

The problem was, Sam had already noticed, in all likelihood on day one, that Dean had changed. That he had returned from hell broken and wounded (albeit he did not know the full extent of that fact, yet). Sam feared that Dean was not strong enough to fight this war, so he found to be the one on whose shoulders everything rested. He was the one who had to gain enough power to kill Lilith, stop the Apocalypse and save Dean from another gruesome death (which Sam assumed waited for his brother at the end of the road) – and Sam was not capable of enduring that again.  
The moment Sam realized that there was not much help to expect from heaven more bricks were added to the load he was already carrying. Even though he had tried to stay away (and had been ordered so by the angels) from using his powers, he was forced back into it. He had to take out Samhain to save himself and his brother – and the whole town.  

Several breaking points for Sam followed – a siren played mind games with the brothers and influenced Sam to mouth, in a cruel way, his suspicions of Dean being incapable to complete the job. He almost lost his brother again after Dean was beaten up by Alistair, and he had not been able to protect Dean from having to return to his torture experience. Then they met Chuck who confirmed Sam’s fears: ‘It must be terrible to know that it all rests on your shoulders.’  

As it was all resting on him – a thought Sam was convinced to be true – he became more practical than ever, changing a part of his nature: had he once been the one going on about morality and humanity, right and wrong he now hardly hesitated to use whatever was necessary – he wanted to train their new found brother Adam, killed a demon recklessly with that hell knife to get to its blood (and not caring about the host this time, as he believed he needed the blood to exorcise the demon that had taken the body of Jimmy’s wife), and, much later, he even considered forming a pact with the Trickster to get an ally.  

There was so much going on amidst the angelic schemes that Sam did not have the time to think – something he always used to do. He was so consumed by Ruby’s plot, since he believed her and needed her that he forgot the man he had always been – an analytic mind, of immense intelligence, out-foxed by the deeply seated belief that he needed demon blood to fight.  

We all know that faith can move mountains… If despair leads you to believe that you need demon blood to save the world and those you love… what would you do?  

If we look at Sam’s state of mind, we can rest assured – he was just as shattered and wounded as Dean, with guilt and the conviction to be a demonic freak eating away at him. From Sam’s point of view, he was responsible for a huge part of the tragedy that followed their family – because of him (being a chosen child for demonic warfare) his mother had died, his father had become a hunter, he had tried to get away from all that and lost Jessica, not to mention the countless life–and–death situations the brothers had been drawn into since they had set out to find John. Dean had sold his soul for him to live. And despite whatever powers had been dormant, only waiting to be awakened, Sam had hesitated too long (listening to his brother’s pleas), not unlike Hamlet – and not managed to save Dean.  

He was a freak, a strange creature not entirely human, and still he had been unsuccessful at saving those he loved most. He needed to do that now. He needed to save Dean now from a most certain death – as Sam assumed Dean would not survive this battle, because he felt, quite correctly, that Dean was weakened. So Sam had to be strong for him, put away the remarks of his conscience and do what was a necessity.  

"When The Levee Breaks" shows in a nutshell Sam’s inner conflict. Guilt sliced through his soul like Alastair’s scalpel did. He still missed Jessica and had not overcome her death and his weight in it. He missed his mother and conjured her up as a soothing person in his illusion, a mother to console him and to tell him that he was right doing what he did. He knew that Dean had begun to look at him like he looked at those monsters they had hunted. Dean had not actually addressed Sam with that word so far, but would do so soon. And – this is what Sam himself feared to be – a freak, a monster, a vampire.  

In addition to that another aspect fuelled his need for following the path he had begun to walk: he was powerful. More than he had ever been. As he grasped Alistair with his telekinetic force to smite him like he was ‘swatting a fly’ he smiled, ‘now I can kill’. Yes, he was powerful. He was calling the shots. And a part of his enjoyed it.  

This was what distinguished him from the little brother, a role Dean still wanted him to assume. Honing his demonic skills was his field of expertise now. Dean could not teach him anything here. This was all Sam’s forte.     ‘

The problem’s not the demon blood. Not really. … The problem’s me, how far I’ll go. There’s something in me… that scares the hell out of me, Dean.’
 (Sam, "GoodGod,Y’All")

    

My hypothesis is that Sam, after having been through his demon cold turkey thing, still felt an echo of his powers, albeit he did not dare to look closer into it. This resonance within himself was awakened whenever he got confronted with demon blood issues.  

It works like this – we carry vivid memories with us that are linked in our cortex with associations and triggers. If you were in love and your partner used to wear a certain perfume… the moment you notice that scent anywhere, the memory of that love will return with a bang, as the neuronal link of important aspects in your memory and external reminders is as short as a nanosecond - which forms another connection with the emotional meaning a memory carries for you.  

The demon blood, I believe, served and still does serve as a form of trigger, a catalyst to remind Sam of powers he controlled once. Powers he longs to control again, but fears. If he needs blood to awaken that power, it’s not entirely him, not his own dark mark. Subconsciously he clings to the blood to prevent realizing that he, in fact, is a paranormal powerhouse.  

‘I think underneath… I just miss the feeling. I know how messed up that sounds, which means how messed up I am.’  

However, it all went south – by killing Lilith Sam eventually opened the last door to the Apocalypse. He had trusted the powers he had honed under Ruby’s guidance – but he had been mislead and made mistakes. The mistake.  

In FreeToBeYouAndMe we are shown a glimpse of the weight he wasn’t able to shed, enforced by the heavy blows the relationship with Dean had taken. Lucifer tricked him with Illusion-Jessica, but spoke what Sam believed to be true:  

J: ‘You can’t run from yourself. Sooner or later the past is gonna catch up with you, as it always does. You know what happens then? People die. Baby, the people closest to you die.’
S: ‘Don’t worry, because I won’t make that mistake again.’
J: ‘Same song, different verse. Things are never gonna change with you. Never.’  

And later:   J: ‘So this is your life now? Think you can just live forever with your head buried in the sand?’
S: ‘I love you, Jess. God knows how much I miss you, too. But you’re wrong. People can change. There is reason for hope.’ 
J: ‘No, there isn’t.’
S: ‘How can you be so sure?’
Jessica morphs into Lucifer: ‘Because you freed me. (…) You’re my vessel, my true vessel.’
S: ‘No, that’ll never happen.’
L: ‘I’m sorry, but it will. I will find you, and when I do, you will let me in.’
S: ‘You need my consent?’
L: ‘Of course, I’m an angel.’
S: ‘I will kill myself before letting you in.’ (this moment of triumph was unfortunately short-lived)
L: ‘I’d only bring you back. Sam, my heart breaks for you… The weight on your shoulders. What you’ve done. What you still have to do. It is more than anyone could bear. If there was some other way… but there isn’t.’  

Sam is afraid of that more than he probably would admit to anyone, it seems. He does not trust himself any longer. He used to be sure to do what was right, and it turned out to be catastrophic, because he still relied to some extent to an external guide, as far as the blood issue was concerned, on Ruby to tell him how to use it, when to take it, etc. (and, let’s not forget, there probably was a not unimportant sexual aspect to it that strengthened their blood bond).  

Now he is all alone with it. He has only himself to rely upon (in regard to the powers issue) and that scares him. Sam dares not to look into the kind of power he might possess. And yet he hungers for it. We have seen that in MyBloodyValentine. The moment he found his capabilities again, he became an almost cosmic force, pulling about a dozen demons at once. What else was he able to do?   He had once moved a cabinet with his mind – and was afraid (logically) that he might end up a killer, like Max or the other bad psychic boy, Webber. If he really had it in him, what would that mean for him, what would that make him?  

For a man who always used to cling hard to his humanity and conscience, the mere idea of being something else, must be utterly disturbing. Even now. If he tells himself that he needs the demon blood to become that other creature, it is not of his doing – and thereby his being human is safe.  

Even though Sam has given in to the temptation the demon blood woke in him again, at his core he still craves forgiveness. Redemption. The love of his brother. The safety of their family which has already been reduced to a small circle in the course of this war.  

He does not see, yet, that he carries a powerful torch within him with those powers, because, as Shakespeare once strikingly pointed out, ‘there is nothing either good or bad, but thinking makes it so’. So far Sam has understood his powers as a dark tool, since they were hell-given, but has not yet thought of them as powers of light – which they would become, if he chose so.  

By now, Sam’s hope is faltering. He is beginning to believe that plan apocalypse will work out and that the angels involved will get the brothers to say yes. So, albeit differently, Sam is captured by a similar state of mind as Dean. His doubts and fears growing, he can barely hold on.  

So far, he has used his Jedi tricks to save others, knowing that Dean would not understand. But Sam did it anyway. All the time Sam had had the immense courage to be loyal which for him meant to do whatever necessary to help the ones nearest to his heart. He chose the harsh path, sprinkled with the painful stones and blades of being misunderstood, of being rejected, imprisoned, forced into a drug intervention, of being hunted by demons and humans alike, in short – of being in the loneliest place possible.  

I, and, I think, most of the fandom are hoping that Sam will come out of this ordeal with new strength and trust in his powers – even though they were given by a demon, they are now at his disposal. They are his. He needs to believe that something so deeply rooted in his being will not hurt him or others he loves, but only those he chooses to target.  

For me, the Winchesters are strong forces of light in a world infected with demons, no matter how dark their actions and attitudes appear at times and Sam has always been, yes, my weak spot. I never stopped rooting for him – so, who will join me in hoping that Sam will find peace, redemption and - most importantly - hope?