Anytime Ben Edlund's name appears as writer for an episode, I know that I will be either laughing till tears run down my face or crying as my heart breaks. "Hello, Cruel World," is most certainly the latter. Pair an Edlund script with the directorial skill of Guy Norman Bee, and Supernatural hits the jack pot every single time. If it was Edlund's intent to break every Supernatural fan's heart with this particular episode, he did that and more. For good measure, he twists the knife deep a few times. He also never lets up. 
His first strike comes from Castiel. The blow is heavy and hard. The Leviathan trapped within the angel's vessel are barely contained. At the crucial moment when they could have finished both Winchesters and Bobby off for good, they are instead forced to retreat. Their black ooze is leaking out, as Castiel is about to explode. He eventually ends up walking into the local lake, which happens to also be the water supply. At this point, almost reminiscent of "Dead in the Water," the Leviathan pour forth from his body and infect the pipes, possessing any who drink the water. 
The body blow here isn't just watching Castiel disappear into the water. It is the trench coat that floats up left behind. Dean picks it up with tears glistening in his eyes, and mutters, "Dumb son of a bitch." 

Dean's anguish here is palpable. It is understated, but raw. Dean doesn't show his emotions as blatantly as he has in the past when Sam died in his arms in "All Hell Breaks Loose I." It is quiet, reserved, and almost resigned to the fact that he has lost one of his friends---and brothers. They may have been on opposite sides until Castiel agreed to return the souls to Purgatory, but that didn't change Dean's feelings---he cared for the angel and losing him hurt more than he cares to admit. After all, he wouldn't necessarily be topside at all if it hadn't been for Castiel. 
They've watched their angel friend possibly die---or become something far worse, too. Only time can tell, but it isn't hard to figure out that Castiel's vessel has now become the vessel for the Boss Leviathan. That remains a mystery yet to be solved, but it's a possibility on the table that makes the scene hurt all the more. 
The body blows don't just stop at Castiel's exit. Edlund continues to surgically remove things from the boys, little by little as the episode moves on. Sam is barely holding on, and as he's trapped by Lucifer in a corner, uncertain as to what is real or not, we see him spiral down into the darkness. As much as the splotch of ink that fades to stark white in the new opening title can signify the Leviathan's ooze, it also reflects Sam's state of mind. It is a mess, and only looks to get worse. 

Dean demands an answer from him about what is happening, and Sam openly states that he isn't sure what's real or not. This rattles both Dean and Bobby. This insanity, as Dean puts it, isn't just a hex or curse. It's possibly incurable and that scares the crap out of him. After everything they've done for each other, including retrieving Sam's soul from the Cage in the first place, might now be for naught and this breaks Dean worse than watching Castiel disappear into the middle of the lake. 
In true Dean fashion, however, he bottles it up and focuses his attention on the hunt.
The Leviathan, hungry and in need of a game plan, are fanning out far and wide. They end up in a high school gym locker room and devour the swim team. They possess a little girl who drinks from a fountain. They take over a man in a garage working on his car. Much like the demons that the boys faced in the past, they are seeking a way to blend into the populace in order to feed from them. 

It isn't until they come across the hospital, Sioux Falls General, that they've hit the true jack pot. (Side note: Sioux Falls has TWO hospitals, neither are called General. There is Avera McKennan and Sanford, formerly Sioux Valley). Unfortunately for her, Sheriff Jodi Mills has recently had an appendectomy done. Her roommate is suspicious of doctors, citing that most cheat on their exams and colorfully says, "He probably doesn't know the difference between your appendix or vagina." 
The little girl from the park, appropriately humming "Ring Around the Rosie" lures the doctor into her vicinity, where she proceeds to break his arm and take his place. We see that the Leviathan have the ability to shape shift and are super strong. The mess left behind as the doctor is eaten is disgusting. We also know, much like the skin walker from "Skin," they download their vessel's memories. This does not bode well for the Winchesters by any means. 
Sheriff Mills smartly stays still when she awakens to hearing her roommate struggling. The doctor, now a Leviathan pod person, is forcing anesthesia upon her for a surprise surgery. Once they disappear out of the room, the Sheriff follows to investigate. She peers into the surgical room to see the monster eating his patient's liver. She also sees something that isn't revealed until later, fleeing back down the hall way. Unfortunately, because she is still recovering from her own surgery, she faints and wakes up in a hospital bed only to have the doctor crooning to her about needing to mind her stitches. 

They give her heavy pain killers, but she manages to get a single phone call out to Bobby, alerting him that there is something severely wrong with Sioux Falls General. Bobby can't simply rush off to investigate. Having sent Dean off to hunt down another Leviathan related incident, he is left to keep an eye on Sam. With this call, he has to choose: Sam or Sheriff Mills and innocents. Sam convinces him that he'll be alright, to go ahead, and Bobby acquiesces. 
It sets up another massive body blow delivered by Edlund. Left alone, Sam can do nothing but time himself assembling his gun. Lucifer is there every step of the way, blurring his sense of reality further and further. It gets so bad, Sam hears the familiar and welcome rumble of the Impala as Dean arrives back from his hunt. But this isn't Dean. It's Lucifer wearing his face. His version of Dean is harsher, blunt, and cold. He says things to break Sam, such as "You're bonkers, but you're all I've got." and "You remember when Martin took his nose dive and started shooting at nothing? I mean his sweater unraveled fast." 
It's all red herrings that this is NOT Dean, but Sam is so befuddled that he can't grasp the logic and pull himself back from the brink alone. Lucifer gives himself away, the building he's conjured is named Morning Star Endeavors, LTD. Morning Star is a name for Lucifer, showing his egotistical nature and a clue that Sam misses. 

Lucifer reveals that it's really him and not Dean, riling Sam up further. Sam fires recklessly at the hallucination, trying to stop the Devil. Lucifer suggests that the best shot would be one to take under Sam's own chin, that killing himself would put an end to his misery. Sam's eyes grow wild, and he shouts at him to shut up, firing at the shadows of his mind again. 

It breaks our hearts to see Sam so broken and alone. He has been stripped of his best strengths: logic and resolve. These two things have gotten Sam through most of his struggles, but it won't be enough this time. Edlund knows how to twist the knife just right so that it hurts, but we keep watching to see how much worse it'll get. 
Bobby, meanwhile, manages to get Sheriff Mills out of the hospital and sets to figure out what is going on. He heads to the morgue, finding a victim of "foot surgery." As he's trying to figure out the truth, the doctor enters and recognizes Bobby. He reveals what the Sheriff saw earlier, a grotesque mouth full of sharp and long teeth and a long tongue intent on devouring the hunter. He also reveals a shocking and terrible truth: the Leviathan know everything about Bobby and the boys from Castiel as suspected earlier. This sets them at a major disadvantage. 

Dean arrives back to Bobby's, finding both Sam and Bobby gone, and follows the tracking device he turned on earlier just for this reason to the warehouse Sam is at. He enters, finding his brother scared and frantic. Sam sees two Deans, one a hallucination and the other very real. He doesn't know which one and fires aimlessly, causing Dean to exclaim, "Sam, this discussion doesn't require a weapons discharge!" 
Edlund presents, with Guy Bee's expert direction here, the most poignant and heartbreaking scene of the episode here. Sam, fractured to a million pieces and uncertain of reality, faces his brother. Dean, who knows what Hell's tortures are like, knows there is a distinct difference in pain in the Pit and pain on Earth. He presses hard into the wound Sam incurred in the Lab after Castiel initially took in the souls of Purgatory. It bleeds and Sam winces, trying to pull his hand away. 
It makes Lucifer fade in and out, weakening his hold upon Sam. Dean keeps up the pressure, telling Sam that this is real and that he is real. Sam realizes that his brother is telling the truth and takes over, shoving his own thumb deep into the wound, blood welling up around it. Lucifer fizzles out and disappears, leaving Sam standing with Dean alone and certain of his reality. 

The most powerful line of the entire episode, delivered by Dean, resonates long after the episode has ended: "I am your flesh-and-blood brother, okay? I'm the only one who can legitimately kick your ass in real time. You got away. We got you out, Sammy. Believe in that. Believe me, okay? You gotta believe me. You've gotta make it stone number one and build on it. "
Bobby phones them, telling them that the hospital is over run with Leviathan and that they should regroup back at his house. Sam agrees and the brothers get into the real Impala and go to meet Bobby. Sam, still reeling from being ground again in reality, assures Dean that he is indeed not seeing anything, not even "white rabbits." 

The biggest body blow that Edlund has to deliver comes here: Bobby's house is in shambles, destroyed completely, burned to the ground. The boys wander the salvage yard, calling for their surrogate father desperately. He is no where to be found, and Dean has finally reached his limit. He calls Bobby's cell, leaving a heartbreaking voice mail. He says, "You cannot be in that crater back there. I can't"¦ If you're gone, I swear I am gonna strap my Beautiful Mind brother into the car and I'm gonna drive us off the pier."
It rips an already tattered heart out and then stomps all over it for good measure. But Edlund isn't done. He then has the Leviathan emerge to fight the brothers. It throws Dean against a car, shattering his leg and immobilizing him. While it seems the monster has the upper hand, the boys know this yard better. A car is hung up ready to be stripped, and Dean pushes the button to drop it onto the Leviathan's head.
But not soon enough. The Leviathan manages to strike Sam hard---and in the temple, causing him to topple to the ground in an unmoving heap. After the car lands, Dean is left to call an ambulance and they are being taken to none other than Sioux Falls General---the last place they want to be. Sam seizures while in the ambulance, Lucifer flickering back into his vision. He admits that he's not real, but he also taunts that he isn't going anywhere and Sam slips completely into his seizure as Dean watches helplessly. 

We're left with terrible questions: Is Castiel truly dead, or worse, become the Boss Leviathan? Has Bobby been killed at his house or is he on his way to rescue the boys from the Leviathan at Sioux Falls General? Will they go after the Sheriff, someone who witnessed their monstrous behavior and realized that it was off? What other terrible things are waiting for the boys? Will Sam descend again into hallucinations and an insanity that he will never recover from? 
The writing, directing, and acting in this episode was superb. Edlund presented a heart breaking script that is on level with "On the Head of a Pin," body blows striking at each turn. As Lucifer says, "It stops when you can't take it anymore." He certainly tested how much the boys could take in this beautiful gem. 
Guy Bee took his script and gave us beautiful direction, pulling on our emotions wonderfully. His use of lighting, music, and camera angles amped up our response to the story. It had all the punches where needed and keep going before we could catch our breath and react before the next body blow. 
His emphasis on close ups pulls the best from Jared and Jensen consequently. He also expertly uses lighting to present the story. The hospital has muted lighting, soft at times, contrasting the awful scenes set in motion. The darkness obscuring Bobby's house hides the majority of its horror, contrasting the grim daylight ruins of the Roadhouse back in season 2. Each deliberate choice Bee makes pulls us deeper into the story and twists us around without us realizing it. 

Acting wise, each added their touch. Misha Collins, although briefly in the beginning, gives a great performance as a melting down Leviathan vessel. His slow, herky jerky walk into the lake makes the scene that much harder to take. The fact that he never looks back also makes this all the more tragic. 
Seeing Kim Rhodes reprise the role of the Sheriff is a treat. She brings a warmth and humor to her character, all with a steel will. Her tenacious character is always welcome. She even gets one of the best lines, "Screw you, Doctor Monster face," bringing in a good dose of humor, albeit briefly, in an otherwise dark episode. She also plays well off of Jim Beaver, and each scene shows how much chemistry they share on screen. I can only hope that she plays more of a part in the story----while staying alive. 

Jim Beaver gives us a distraught and worried Bobby, watching his two surrogate sons struggle with the aftermath. Sam is breaking into a million pieces in front of him and he's unable to stop it, while also watching Dean fracture just as badly in a different way. His grief is hidden by anger and anxiety. No matter what he tries to say or do, Bobby can't reach him until Dean thinks he's possibly dead. He always brings the paranoid hunter to life in such a way that it's hard now to imagine the show without Bobby's presence. With his fate hanging in doubt for Friday, it certainly makes one nervous! 

Mark Pellegrino continues to play a delicious and frightening Lucifer. His nonchalant style and laid back nature makes his performance all the more terrifying. He speaks with a honey tongue and it makes even us the viewer question if he might be telling the truth. Each time Pellegrino appears is a delight and makes the story that much more rich. He also plays off so well from Jared.

Jensen gives us a stoic and barely holding it together Dean. Without Baby to fix, he is left with Sam and Bobby---and nothing to do but wait. He doesn't want to deal with the loss of Castiel, and Jensen gives us the classic tense jaw and shoulders, the grim expression, and the flippant brush offs that mark all of Dean's encounters with emotional moments. Dean can't fall apart since Sam already has, and Jensen gives us a concerned and frantic Dean. 
He also sells us a sinister Lucifer and callous Dean when Sam sees him in his hallucination. It is a stark difference from the real Dean in every way. While Sam is unable to tell the difference, twisted and turned upside down as he is, we the viewer can tell that there is something significantly wrong in simply the way Jensen carries himself. He sells us Dean, but falls just slightly short, just as Lucifer really would. It is one of Sam's worst nightmares, and as such, Sam hears the worst from the one person he can be ill afford to hear it from: his big brother. It's so convincing at points, however, that until Lucifer reveals the truth we almost fall into the trap with Sam. 

Jared brings us a fractured and tortured Sam. His eyes tell the story almost more than any dialogue he will speak. They are pools of frightened emotion, belying the stress the younger Winchester brother is enduring. Guy Bee makes it a point to emphasize Jared's face, particularly his eyes to bring this into focus. He breaks the heart with simple glances, minute facial expressions, and understated acting that lets us glimpse the shattering taking place within Sam. It would have been easy to drift into exaggeration and over the top, but Jared is smart to dial it back and give us a subtle sucker punch to the gut each time we see his face crumble just a bit more as Lucifer taunts Sam ruthlessly. 

The best scene, of course, takes place in the warehouse, and Jared and Jensen reignite fully the chemistry they've had since the Pilot. The brothers are facing the hardest challenges they've ever faced, both from within and without. It will take both of them working together to solve it, but they must deal with their own issues first. Jensen has Dean approach Sam like he is a caged animal, wounded. The concern in his expression sucks us into the scene, just as Jared gives us a freaked and broken Sam, unsure and uncertain as to what really is there and what is not. His exclamation, "But I thought I was with you!" and the way his voice breaks on those words tugs on the heart strings. 

Seeing the two of them play off of one another, pulling out each other's strengths makes the scene riveting yet almost hard to watch. It certainly is one of the best scenes the series has ever produced, and it can only be hoped that we'll see more like it as season 7 progresses. 
With so much hanging in the balance, it's hard to imagine what body blows await the boys"”and us the viewer in the upcoming episodes.