Although Loki enjoys meddling with the life of his adopted brother Thor, the god of mischief isn't above including other Asgardians like the warrior Sif in his usually nefarious plans. While the MCU's version of Sif had a rather specific grievance with Tom Hiddleston's Loki, her comics counterpart has a greater history and even more reason to distrust and even despise the infamous trickster.  Loki had once stolen Sif's body for his own agenda while trapping her spirit inside a human body, which was slowly dying while being unaware of who she really was as Loki watched from the shadows.

After the events of Ragnarok,  J. Michael Straczynski’s Thor saw Dr. Donald Blake travel into "the Void" to find his famous alter-ego. Convinced that with Ragnarok completed he could rebuild Asgard and bring back its people, Thor fought to be reunited with Mjolnir and soon returned to Earth. After relocating Asgard to Midgard, specifically Oklahoma, the former Avenger began his journey around the world to find his friends and allies who had been unknowingly trapped in human bodies. After reuniting with others like Heimdall or the Warrior's Three, Thor was able to find Loki who had taken on a female form. Although naturally suspicious considering their history, Thor chose to give his sibling a second chance at a new life with stern warnings of repercussions should old behaviors resurface.

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Thinking that Sif could have been reborn in the body of Donald's ex-girlfriend Jane Foster, he checked but did not find any traces of Sif within the busy nurse. Little did they both know that Sif had actually been reborn in the body of Mrs. Chambers, an elderly woman in Jane's hospital dying from terminal cancer. This had been kept hidden by Loki who not only used his magic to mask Sif from Thor or Heimdall's attention but Loki had also commandeered her body for his own use. While Loki was seen as a member of Norman Osborn's Dark Cabal or whispering conjecture or half-truths in Thor's ear, he was also seen visiting Mrs. Chambers, using an enchanted mirror to trick Sif into seeing her own face instead of the body she was trapped and dying in.

King Loki prepares to attack in Marvel Comics.

In Marvel's Loki, Tom Hiddleston's title character found himself trapped in an endless memory where Sif, played by Jamie Alexander, admonishes Loki for cutting her hair, hitting him in response before storming off. Although this small yet hilarious cameo happens to be mythologically accurate, it pales in comparison to this gross violation of Sif's body and mind. Loki had no problem resuming his true form if necessary and regarded Sif's body as both a vessel and a guarantee, knowing that any act of vengeance visited upon him by Thor would threaten to kill both him and damage his beloved Sif's body beyond use. Loki goes to great length to keep Sif alive but also miserable, continuing his previous game of manipulation, revenge, pain and suffering to Thor and the other Asgardians who barely tolerate and trust him as is.

Loki visits the exiled Thor and reveals the truth that his current body was meant for Sif and any transference from his female to his male form would likely kill Sif's host, endangering her as well. Showing up to the hospital with a repaired Mjolnir, Thor is able to free Sif's spirit although the experience results in Mrs. Chambers death. Despite a tearful reunion with Thor, Sif is revealed to be traumatized by the entire experience, the violation proving to be harder to move past than a mean-spirited prank. Although Sif would continue to serve and protect Asgard, one can understand why the MCU chose to display their rivalry in a different manner, considering how dark and traumatizing this betrayal by Loki truly was.

NEXT: Loki Secretly Used Time Travel to Trick Odin Into Adopting Him