The Biggest Mistake Dean Ever Made On Supernatural

Over the course of a staggering 15 seasons, the paranormal drama "Supernatural" was one of the landmark television shows of the early 21st century, developing a massive and passionate fandom that dominated sites like Tumblr during the height of its popularity. Centered around two monster-hunting brothers, Sam and Dean Winchester (Jared Padalecki and Jensen Ackles, respectively), the show quite literally took fans from the depths of Hell to the highest reaches of Heaven and everywhere in between.

With both brothers prone to the pitfalls of the human condition, they each made plenty of mistakes during the 327 episodes comprising "Supernatural," but some are more drastic than others. A lot of the brothers' biggest blunders are born of their special bond, and in trying to protect each other they've inadvertently brought about horrible consequences. Sam makes his own grievous mistakes, but Dean is especially guilty of putting his brother over others. He prevented the gates of Hell from being closed to save Sam, even though it meant allowing demons to roam the Earth. Later, when he was afflicted with the Mark of Cain, he refused Sam's help, leading to his death and resurrection as a demon.

However, amid a long list of Dean's missteps, one was far worse and had more dire consequences than any other. Here's the biggest mistake Dean Winchester ever made on "Supernatural."

The Apocalypse in "Supernatural" is a cataclysmic battle between Heaven and Hell that begins once Lucifer is released from The Cage in which he is kept prisoner. In order to release Lucifer, the 66 Seals of The Cage must be broken, each requiring a different condition to be met. The first Seal requires that a righteous man spill blood in Hell, and it is Dean who breaks it.

Near the end of Season 2, Sam is killed. Dean is distraught, and in the season finale, "All Hell Breaks Loose: Part 2," he makes a deal with a crossroads demon (Ona Grauer) to bring Sam back. The demon agrees on the condition that Dean will die in one year. Sure enough, in the Season 3 finale set a year after his deal, Lilith (Katie Cassidy) unleashes a hellhound on Dean which kills him and drags him into Hell. After 30 years of being tortured, Dean finally agrees to torture other souls in exchange for a reprieve. As he tells Sam, "I started ripping them apart. I lost count of how many souls." Unbeknownst to Dean, torturing those souls unlocks the first seal on Lucifer's cage, beginning the sequence of events leading to the Apocalypse.

Making things worse is the fact that before Dean was sent down there, John Winchester (Jeffrey Dean Morgan) was tortured in Hell for 100 years and never gave in. Compared to his father, Dean's resolve was easy to break, and the price he paid for his sins was the death of thousands and the near destruction of the world. Committing such heinous violence also burdened Dean with immense guilt. Out of all his mistakes on "Supernatural," none were so obviously ethically impermissible as torturing fallen souls, and none had a more calamitous outcome.