Authors Note:
I fully admit to using various episode titles from Supernatural's run for all but maybe two episodes. I am also thinking of periodically going back and overtime and playing with what some seals could be.
The following was discovered on the Wikipedia page for the show Supernatural in the recently discovered paraell universe Earth designed Earth-2. Differences between this and our Earth appear to be minimal, aside from a smattering of historical events and in the realm of pop culture. The CW show Supernatural is one area of difference.
In both universes, the show is the same until the second episode of Supernatural's fourth season. What you see below was largely copied and pasted from the Wikipedia entry for said fourth season on Earth-2. Some episodes that appear in Supernatural's fifth season in our universe appear to have been fourth season episodes on Earth-2. The descriptions for those episodes have been left blank. In other cases episodes occur almost exactly as they did in our universe, with only a few minor details changed. And almost all episodes from Earth-2's Supernatural use titles that appeared throughout Supernatural's ongoing run in our universe, though the plots might be different..
4.02 "Are You There, God? It's Me, Dean Winchester"
Castiel returns with Dean to see Sam and Bobby. He explains to the three the nature of the threat: 666 seals keep Luciefer in his cage. The first seal has been broken, and the demons are breaking the others. If enough are broken, Lucifer will walk the Earth, and demons will posses most of humanity, torturing them for a long time. But the seals are all interconnected like a complex machine, and must be broken in a certain order. Mess up the order, and suddently things must be broken in a different order. So Sam, Dean, Cas, and a select few angels and humans around the world have been chosen to deal with this. With Castiel's help, the team stops a seal from being broken. At the end of the episode, Dean stares off, remembering hell
4.03 Heaven and Hell
Castiel and Dean stop a seal from being unleashed, but in the process, some demons succeed in getting more unlocked. Dean learns about how heaven attempts to balance helping humanity without compromising their free will, relying on wandering angels like Castiel to assist subtly, and that natural disasters are not punishments from God, but the result of "moving every atom in repeating patterns", and said patterns "smashing into one another". At the end of the episode, Castiel starts to tell Dean there is something he should know, and that he waited because he wanted to see if and when Sam would come clean. Episode ends before we learn what Castiel is referring to.
4.04 Metamorphosis
Episode opens with Ruby and Sam toruturing a demon using Sam's psychic powers. Episode is mostly a flashback to their courtship. They easily stop a seal from being broken. The episode ends with Dean and Castiel confronting them.
4.05 I Know What You Did Last Summer
Dean stares at Sam and then leaves. Castiel explains that he knows Ruby's intentions are good, but that he is concerned about the demon blood. Sam finds Dean who is pissed Sam kept this secret and is using his psychic powers. The team becomes distracted when a group of demons attack. Dean seems silently inpressed with Ruby a little bit, but both he and Castiel remain worried about the use of demon blood. Dean also tells Sam about how he remembers Hell, where time works differently, and he spent 30 years being tortured before he gave up fighting and then was spared further agony by torturing souls for 10 years.
4.06 On the Head of a Pin
A seal has been broken, but something is wrong. While surveying the damage, Castiel determines a fallen angel was responsible. We learn that Hell has things other than fallen humans. But this one fell recently. Zakariah, Castiel's boss (and messenger of the mysterious 'Council' ", arrives and confirms an angel has gone rouge. Castiel, Sam, and Dean investigate and discover the angel responsible, an old friend of Castiel's named Uriel. They manage to banish him to hell. Episode ends with Dean learning he broke the first seal.
4.07. Just Say No
While exacting information out of a demon that will be useful to other hunters, it becomes clear that the demon blood is having a negative impact on Sam. Even Ruby is starting to reconsider her plan. Ruby, Castiel, Sam, and Dean try, but fail, to stop Lilith from breaking a seal. In the process, Sam learns that Azazel's plan was in fact to forge a vessel for Lucifer.
4.08 Weekend at Bobbys
While Ruby, Bobby, and Castiel bond over a hunt where they stop a seal from being broken, Sam goes through detox in Bobby's panic room.
4.09 The Girl Next Door
Dean and Bobby team up with another angel/human team to stop a seal from being broken, fighting both demons and a nest of shapeshing vampires working for Lilith. Ruby watches Sam and helps him finish his detox, solidifying their bond and declaring they love each other.
4.10 There Will Be Blood
Lilith, not only breaks a seal, but in the process unleashes the horesman War. Sam, Dean, and Ruby team up with Ellen and Rufus to save a small town that seems to be possessed by demons. It turns out there are no demons, but War is causing hallucinations. Sam, Dean, Ruby, Ellen, and Rufus succeed in cutting off War's ring, which seems to cause him to dissipate.
4.11 Hammer of the Gods
Castiel, learns through "angel radio" of a murderous cult surrounding the Pagan God Zeus that has appeared in Las Vegas. He, Sam, and Dean, track Zeus down and destroy him, further exploring the nature of the pagans, a hodgepodge of difference groups such as demons, humans adept in magic, shapeshifters and vampires posing as deities, extra dimensional beings that appear as humans, and all manner of their various mixed-species children.
4.12 99 Problems
Pestilence and Famine have been unleashed. While trying to track them down, Sam and Dean stop some fallen angels turned demons from unlocking a seal.
4.13 Sympathy For The Devil
Lilith decides to take the team head on. She lures them into a trap, and a battle is fought, where Bobby's legs are broken. Throughout the episode, Sam starts seeing Lucifer. While Lucifer's full power is locked within the cage, enough seals have been broken that his consciousness is able to possess someone. Lilith is killed and Ruby goes off to find more information about beating Lucifer.
4.14 Abandon All Hope
4.15 Purge
Sam and Dean confront Pestilance, and manage to cut off his ring. However, he tells them "your too late" before he dissipates. Crowley finds them and warns them about a processing plant that will be the launch pad for one of the weapons of Hell, the croatoin virus. Sam, Dean, Bobby, and Ruby, temporarily returned before continuing her own hunts, shut the factory down.
4.16 My Bloody Valentine
4.17 Always Let Your Conscience Be Your Guide
Shaken up by Famine's diagnosis, Dean sits out a mission while Sam, Ruby, and Crowley stop a seal from being broken, though they get word of two more that were broken. Castiel enables Dean to physically see and interact act with a lower order of angels: sentient balls of light that whisper at peoples sub consciousness to try and influence them to good. Castiel explains that there are three main orders of angels: these "jiminy crickets", Castiel's who take vessels and wander the Earth, and the "Council" which consist of Heaven's most powerful angels, including Michael, and that he gets his orders from this Council (being cryptic about whether their orders are directly from God, they act independently, etc.) The entire experience leaves Dean realizing that if he survives this war, he would like to try to be with Lisa and Ben.
4.18 Dead Men Don't Wear Plaid
4.19 Two Minutes To Midnight
Castiel and Ruby fail to stop a seal from being broken, with the demons telling them they are almost finished. Dean finally finds Death, who Lucifer has enslaved with a spell. Furious at this, Death agrees to give Dean his ring, and to reveal a secret weapon he knows will kill Lucifer, though he warns Dean it will come at a cost.
4.20 Swan Song
Sam, Dean, Bobby, Castiel, and Ruby are shown narrowing in on the Devils location. As they fight their way towards Satin, flashbacks reveal Sam getting a demon blood power up, and the group seeming to say somber goodbyes. As they get closer, Sam appears to become corrupted by Lucifer's mind and the effects of the demon blood. As the demons break the final seal, and Lucifer appears to emerge from Hell and to enter Sam's body, the trap is sprung: Death it turns out had Dean melt down the horsemen's rings into bullets, which he fires from the colt. Lucifer is killed. After giving Sam a hunters funeral, the team is shown going their separate ways, with Bobbys legs restored by Crowley as a bribe to keep Dean off his back, Castiel continuing his wanderings, and Ruby "elevated" for her work to a rank Dean sarcastically refers to as "Dark Angel" (a reference to Jensen Ackles previous role on the show Dark Angel). She is also revealed to be pregnant with her and Sam's baby. The show ends with "Carry On My Wayword Son" playing, while Dean drives off alone into the sunset, a map on the seat next to him having the name of Lisa and Ben's hometown circled on it, implying he is going there.