Sam and Rowena

Sam Winchester and the witch Rowena MacLeod have a complicated relationship.

Background
The relationship between Sam and Rowena is a complicated one in general. Due to Rowena's evil nature originally, the two often found themselves at odds and only reluctantly working together for situations of mutual benefit. As Rowena proves to be untrustworthy, Sam often works with her under supervision and iron chains.

Following her Rowena's death at the hands of Lucifer and her subsequent resurrection, a situation in which she had betrayed the Winchesters and Crowley to help Lucifer, their alliance became somewhat less reluctant and more willing in nature with Rowena helping the Winchesters against Lucifer and the Darkness to save the world. With Rowena having a change of heart following the war with the Darkness, she became more of a willing ally, coming to the Winchesters aid against the Loughlin Family and helping with her grandson Gavin after Sam calls upon Rowena for help. In both cases, she had something to gain for herself, but also put herself into danger against the Loughlin's to help save Dean.

After Rowena's second death at the hands of Lucifer and subsequent resurrection, her relationship with Sam became closer due to the two sharing a traumatizing experiences at the hands of the archangel. As a result, Sam gave Rowena the ritual she needed to remove the bindings on her powers so that she could protect herself. Not long later, the relationship took on a whole new dimension when Sam and Rowena learned every version of her final fate had Sam as Rowena's one true killer. Despite this, Rowena couldn't bring herself to kill Sam and began seeking redemption at his suggestion, becoming more selfless in her actions and helping while asking for nothing in return. Following the death of Mary Winchester, Rowena attempted to help bring her back because of how devastated Sam and Dean were, even creating a resurrection spell for the job as was later revealed. In addition, Rowena and Sam's relationship took on a more mentor-student turn with Sam learning various things about the practice of witchcraft from Rowena. During the Sanetur Acre Vulnus spell, Rowena called Sam the closest thing they had to a witch besides her and trusted Sam to act as her assistant in casting the spell.

At the end of Rowena's life, Sam and Rowena had changed from mortal enemies to close friends who cared deeply about each other. When Rowena ultimately met her fate at Sam's hands, it was at her own request so she could sacrifice herself to save the world, a request that drove Sam to tears. When Sam fatally stabbed Rowena, he hugged her at the same time as a final gesture of comfort. Rowena's death had a profound impact on Sam who continued to reel from her loss for some time afterwards.

Sam would be later be called Rowena's protégé by Dean while it was implied that Rowena intended for Sam alone to inherit her magical stash, including the journals chronicling Rowena's lifelong spellwork. Rowena's journals helped Sam again by allowing him to use one of her spells to resurrect old friend Eileen Leahy. At the same time, Sam was able to kill a witch using a powerful spell and hex bag he created, something Sam credited as having learned from the best, Rowena.

Season 10
In Girls, Girls, Girls, Rowena first comes to Sam's attention when she kills the demon Raul with the Defigere Et Depurgare spell. Sam identifies Rowena as the culprit as she is the only witch to know that particular spell. The meeting between the two is brief before Rowena casts the Attack Dog Spell on Elle and runs off chased by Dean, leaving Sam to fight off the girl who ultimately dies from the spell. Subsequently, in About a Boy, the Winchesters learn from Katja that she was sent by the Grand Coven to hunt Rowena.

In Book of the Damned, Sam is surprised to learn that Rowena is Crowley's mother and had revealed that the Mark of Cain was a curse. After being unable to decode the Book of the Damned, Sam seeks out Rowena's help at the end of Book of the Damned and the beginning of The Werther Project. Rowena offers Sam a deal to help remove the Mark of Cain in exchange for Sam killing Crowley which he accepts, but becomes frustrated when she reveals that she can't currently read the Book of the Damned. Following Rowena's instructions, Sam searches for Nadia's Codex which can be used to read the Book of the Damned, seeking Rowena's advice for a disenchantment spell, but rejecting her help otherwise. Sam's hallucinations under the Werther Box take the form of Rowena supposedly helping and encouraging him. After getting the codex, Sam brings it to Rowena, but chains her up until she can find the spell as he doesn't trust her.

In Dark Dynasty, Sam becomes frustrated when Rowena reveals that she can't read the codex and assembles a team to help her, but has to spend time away due to Dean's growing suspicions.

In The Prisoner, following the death of Charlie Bradbury, Sam prepares to end the ongoing efforts on Dean's orders and makes it clear to Castiel that he intends to kill Rowena. However, after getting an email from Charlie containing her decoder, Sam changes his mind when Rowena confirms that she can use it to read the Book of the Damned. However, Rowena forces Sam to keep up his end of the deal by refusing to do so until Sam kills Crowley. Sam attempts to kill Crowley with the Defigere Et Depurgare spell as per Rowena's instructions, but fails and Rowena refuses to do anything until Sam succeeds.

In Brother's Keeper, Sam creates the witch-killing bullets to try to threaten Rowena into helping, but she is unthreatened as she knows that Sam needs her help and can't actually kill her. Instead, Rowena negotiates for her freedom and the codex which Sam accepts when she confirms that she knows which spell she needs. Sam helps with planning for assembling the ingredients, but has to leave to deal with Dean. Rowena subsequently removes the Mark of Cain, but casts the Attack Dog Spell on Castiel, forcing him to attack Crowley while she escapes with the Book of the Damned.

Season 11
In The Bad Seed, Sam captures Rowena to force her to break the Attack Dog Spell on Castiel, making a deal with her to do so in exchange for her freedom. Sam is frustrated however when they only recover Charlie's decoder and Nadia's Codex from Rowena's belongings, but not the Book of the Damned. When Castiel escapes due to the spell overtaking him again, Rowena reveals her deal with Sam to Dean while they search for him though she fails to drive a wedge between the Winchesters. When they find Castiel, Sam holds Rowena at gunpoint with witch-killing bullets to ensure her cooperation, but she disarms him and escapes afterwards. Despite Rowena's escape, Sam is still left pleased as they got Castiel back to normal and without the decoder and codex, Rowena's use of the Book of the Damned should be more limited.

In O Brother, Where Art Thou?, Sam, Dean and Crowley are forced to seek out Rowena's help to speak to Lucifer in Hell. Though Sam allows Rowena access to the decoder and codex so she can translate the spell in the Book of the Damned, he's careful to keep her on task and away from reading the other spells. While Rowena succeeds in helping Sam speak to Lucifer, the warding suddenly fails and Sam is captured by the archangel. In The Devil in the Details, its revealed that Rowena betrayed them and was working with Lucifer the whole time to help Lucifer escape the Cage with Sam as his vessel. Using a Witchcatcher, Dean and Crowley force Rowena to help them send Lucifer back into the Cage, but are left unaware that he took Castiel as his vessel and escaped before killing Rowena.

In Hell's Angel, Crowley reveals Rowena's death to the Winchesters while negotiating with them for a Hand of God in exchange for helping to get rid of Lucifer. Sam is annoyed as they need both Rowena and the Book of the Damned to lock Lucifer away again as Crowley wants and they have neither. Sam is the first to notice a resurrected Rowena's message as Dean and Crowley argue. While preparing to combat Lucifer, Sam and Rowena don't interact much, but he seems uncomfortable with her presence and not totally pleased to see her.

In We Happy Few, Sam is the one to suggest seeking out Rowena's help against the Darkness, calling Rowena "a snake," but a powerful witch who has the Book of the Damned on her side. Sam is the one to approach Rowena for help and get her and Clea on board with the plan. In Alpha and Omega, after God is mortally wounded by the Darkness, the Winchesters and Rowena continue their alliance as they try to save the universe from destruction. Rowena helps build the Soul Bomb to kill the Darkness and remains with Sam, Crowley and Castiel until they see the sun being restored, showing Dean's success.

Season 12
Sam's next encounter with Rowena is when the brothers need her help in banishing Lucifer back to his Cage. Rowena's full desire to do this enables the plan to become successful. Weeks after, Sam enlists Rowena's help again after Dean begins suffering from a memory loss curse. The two track down the Loughlin Family, but are easily overwhelmed. It is Dean who kills the witches, and afterwards, Rowena uses the Loughlin Family's spellbook to free Dean of the curse. Rowena intended to take the book back with her, but Sam stopped her before she could get away with it. This time, however, Sam admits that he owes Rowena for her help.

Sam contacts Rowena again when he and Sam learn they must find Rowena's grandson Gavin MacLeod in dealing with a vengeful spirit. Rowena did not want to partake in such, until Sam promised compensation for her help and then told her about Gavin. With Gavin's help, Sam and Dean were able to identify the ghost and find a solution on how to stop it - by sending Gavin back in time. Rowena shared their view that Gavin should return, and even helped the brothers keep Gavin away from his father Crowley, who did not want to lose Gavin.

By the time Sam needs her assistance again, Rowena is revealed to have been brutally murdered by Lucifer. Sam is visibly furious about this, especially since he had intended to use Rowena to lock up Lucifer for good, this being the very reason Lucifer had killed Rowena in the first place. Fortunately, Rowena is still able to resurrect herself and helps the brothers with another witch case. Sam and Rowena briefly bond over their shared trauma of seeing Lucifer's true face. Sam admits to Dean that if Rowena plans to backstab them again he will hunt her down and shoot her himself but he also hopes that if Rowena ever re-encounters Lucifer, she will make the archangel suffer.

Season 13
During Funeralia, after Rowena goes about killing people, Sam feels guilty since he let her obtain her full power. It is revealed by Jessica, that Sam is always the one to permanently kill Rowena and he is shocked to learn this. When Rowena calls them and tells them she wants her son back, Sam asks her to stop while Dean threatens her with the revelation of Sam being the one to permanently kill her which leaves her mildly surprised and interested.

In Exodus, Rowena keeps the rift opened long enough for the Winchesters and company to return to the main universe. While everyone is celebrating, Sam and Rowena talk and he congratulates Rowena for holding the rift open long enough to get everyone back. Sam admits that they owe her one and Rowena tells him that she plans to collect on it eventually, but smiles at Sam as she says it.