I don't know if I read it on your blog or heard it somewhere else that if "Supernatural" ended with "Swan Song" Sam and Dean would have both jumped into the pit together. Is this true? I know Kripke said in an EW interview that fans would have hated his ending.
The original ending was for Sam to go Darkside saving Dean from hell and for Dean to have to put Sam down like Sam did Madison.
Then the writer's strike happened and they didn't have enough time for Sam to believably go dark enough to be the big bad. Mystery Spot was supposed to be the start of Sam's dark arc.
The end of s5 was supposed to be Dean possessed by Michael with Lucifer possessed by Sam. They would show up to battle to the death, only Sam and Dean would break through with the power of brotherly love and jump into the cage together.
Bobby and Castiel weren't supposed to come back end of s5, but stay perma dead. It was going to be a bloodbath.
Thankfully, Supernatural was renewed for another season, so they made up Adam so that Dean could be alive and not possessed by Michael. Sera requested Bobby and Castiel brought back to life.
Fun fact, s15 was also supposed to have Lucifer and Michael in bigger roles, but they were (thankfully imo) cut down due to covid. Lucifer and Michael were supposed to both die fighting Chuck to buy time for Sam, Dean, and Jack. Eugenie would've had the redemption arc she always wanted for Lucifer.











