Free will versus destiny, and the power of human choice. Season 6: The Aftermath of the Apocalypse
With Dean’s crossroads contract ticking down, the brothers frantically search for a way to break the deal. They face off against the demon Lilith while introducing long-running characters like the thief Bela Talbot and the demon Ruby. Supernatural all seasons 1- 2- 3- 4- 5- 6- 7- 8- 9
Sam, left alone and believing Dean was gone forever, abandoned the hunting life for a year, finding a quiet existence with a woman named Amelia. Dean, however, survived the brutal landscape of Purgatory with the help of a vampire named Benny, eventually fighting his way back to Earth. The brothers reunited with mixed emotions and immediately faced a new divine challenge. Kevin Tran had deciphered the demon tablet, revealing a series of three Herculean trials that could permanently lock the gates of Hell forever. Sam took on the grueling trials, which slowly began to destroy his body from the inside out. As Sam prepared to complete the final trial, which would require his life, Dean stopped him, declaring that no victory was worth losing his brother. Simultaneously, the rogue angel Metatron tricked Castiel, stealing his grace and using a spell to cast all the angels out of Heaven, causing them to fall to Earth like falling stars. Free will versus destiny, and the power of human choice
The highest-rated season by many fans, Season 5 throws Sam, Dean, and Castiel into a full-blown war for the world. They are hunted by the Four Horsemen (including a brilliantly portrayed Death), and they learn the awful truth: Sam is the true vessel for Lucifer, and Dean is the vessel for the Archangel Michael. Their destiny is to say "yes" to their respective angels and fight to the death, destroying half the planet in the process. The season finale is a masterpiece of storytelling: Sam says "yes" to Lucifer to gain the upper hand, and Dean refuses Michael. Sam jumps back into Lucifer's cage in Hell, taking the Devil with him. It’s a bittersweet, heroic, and seemingly final ending. Sam, left alone and believing Dean was gone
With their father dead (traded for Dean’s life), the brothers become true independents. This season introduces the "Special Children"—psychics bred by the demon Azazel. It also gives us the first angelic weapon (The Colt) and the tragic figure of Ava Wilson.