The airing of Supernatural universe back to life after the original series ended two years ago. The prequel’s outline is based around John and Mary Winchester learning to trust new hunters, but Supernatural mainly showed Sam and Dean dealing with quite a lot of traitors.
Most of the deceivers were double agents who either betrayed or aligned with the Winchesters, ranging from those with good but misguided intentions, like Castiel, to purely evil characters, such as Ruby. The best demons, angels, or hunter double agents had plans that relied on who they were working for, along with how effective their deception ultimately was.
Garth Fitzgerald IV Infiltrated Alternate Michael's Plans
Garth was a character Supernatural nearly forgot about for years after he became a werewolf. But he returned as the Winchesters’ double agent when they needed a monster to infiltrate Alternate Michael’s experiments on their kind using his grace.
Garth managed to successfully infiltrate the meeting by suggesting he had turned on the Winchesters when he was really ing information to them. Although he was useful to the heroes, Garth also ended up getting injected by Michael’s grace himself, which meant he had to be detained until he regained his bearings.
Samuel Campbell Turned On His Own Family
Despite being Sam and Dean's grandfather, Samuel worked as Crowley’s double agent against them. Samuel’s reasons to turn on his grandsons were so that Crowley would resurrect Mary in return for delivering the enemies of the King of Hell to him.
Samuel never quite became close to Sam or Dean, but he used their familial ties to gain their trust long enough to trap them in Crowley’s mercy. This came to bite him back, though, as Dean and Sam successfully escape and thereafter saw Samuel as their enemy until Sam ultimately took his life.
Bela Talbot Discreetly Worked For Lilith
Bela was always a duplicitous person who kept getting the better of Sam and Dean, but she appeared to be working purely for herself. It turned out she was actually creating something of a connection with the brothers to kill them for Lilith.
Bela wasn’t a traditional ally to the Winchesters, yet she wasn’t one they thought would want to eliminate them. Bela’s double agent work was so she could get out of her 10-year deal with Lilith to be sentenced to Hell, although she still ended up getting killed. To her credit, she did manage to get close enough to Sam and Dean, failing right at the end when they finally caught on to her tricks.
Uriel Aligned With The Demons
Uriel was introduced as one of the angels working to stop Lucifer from returning to Earth. He had a hatred for the Winchesters from the get-go but was Castiel’s subordinate. Later on, it turned out that Uriel had abandoned Heaven’s mission in favor of the demons’ to bring Lucifer back.
Uriel became a double agent because he believed that Lucifer was right to consider humans unworthy. His discreet work involved killing his own angel siblings and releasing Alastair to help Lilith’s quest in breaking the 66 seals of Lucifer’s cage. Uriel came close but was exposed and killed by Anna for his treachery.
Castiel Was In Cahoots With Crowley
There’s no question that Castiel’s inclusion is one of the major things that fans love in Supernatural, so it hit viewers particularly hard when he was revealed to be working with Crowley in season 6. Castiel pretended to be aligned with the Winchesters while keeping his partnership with Crowley hidden.
Castiel’s double agent saw him fake Crowley’s death to win the Winchesters’ trust while also spying on them to learn of their plans. To be fair, he also betrayed Crowley to prevent him from exploiting all the souls from Purgatory, making Castiel’s turncoat nature an act of necessary evil.
Gadreel Betrayed Dean's Trust
Gadreel posed as Ezekiel and convinced Dean to let him possess Sam to heal his body. In reality, Gadreel was working with Metatron to complete the latter’s mission of taking over Heaven and the Earth by spying on the Winchesters and eliminating their allies.
Gadreel used Sam to smite Kevin and steal the angel tablet, which made him a particularly hard-hitting double agent. He then turned on Metatron to help the Winchesters after realizing that Metatron had used him, ultimately killing himself to aid the heroes.
Arthur Ketch Turned On Multiple Parties
Arthur Ketch is one of the best side characters in Supernatural, and was a Men of Letters operative who pretty much worked for those who held the position of power. After the Men of Letters were brought down, Ketch aligned himself with Asmodeus and initially worked as a double agent against the Winchesters before going the other way.
Ketch managed to win the trust of everyone from Mary, the Men of Letters, the Winchester siblings, and Asmodeus, becoming a double agent for every party at one point. He was largely effective and successfully escaped each time, although his cover was also blown.
Lucifer Became Chuck's Inside Man
Lucifer was a double agent only for the final episode he was in, but was extremely useful to Chuck. The devil was resurrected by God to pretend he wanted to aid the Winchesters, only to reveal that he’d played them long enough to steal the death book containing the way to defeat Chuck.
Lucifer was impressive in his deception since he got the Winchesters to briefly trust him, which was remarkable given how much he’d tortured the brothers in the past. Lucifer was nearly successful in his mission until Michael surprised him by stabbing him with the archangel blade.
Michael Nearly Delivered Chuck The Ultimate Victory
Michael was a double agent for an even lesser time than Lucifer but was more successful than his brother. He initially wanted to bring down God but gave in to his need to please him and informed Chuck of the Winchesters’ plan to defeat him.
Michael let Chuck know of the location he needed to arrive at to stop the Winchesters and completed his goal. However, the fact that he took so long to become a double agent didn’t sit well with Chuck, who proceeded to kill his own son for his original plans to defeat him.
Ruby Completed Lilith's Master Plan
Ruby might just be the most intelligent demon on Supernatural, seeing as she fooled every character for years before completing Lilith’s grand plan. Ruby acted as a demon who had turned on Lilith to become the Winchesters’ ally, revealing right at the end that she was Lilith’s agent all along.
Ruby got Sam hooked on demon blood, made him break the final seal, and turned the brothers against each other, all the while pretending to fight for the heroes’ benefit. She was killed by Dean and Sam for her treachery, but it was still too late since Ruby successfully brought Lucifer back to Earth.
