Loki and Thor are brothers, and Loki and Sylvie are variants of each other from alternative timelines. Due to the time-travel aspect of the Loki series, there are some variations in the canon/history of each character in this relationship.
The three characters are all Asgardian although Slyvie didn't end up growing up in Asgard as she was taken away by Time Variance Authority (TVA) early in life. Thor from the main timeline lives in the knowledge of Loki being dead. He isn't aware that there are variant versions of Loki, and that one of them is working at the TVA as a result of the Avengers doing time travel. The variant of Loki meets Sylvie while trying to stop her tampering with TVA, but ends up joining her. Sylvie never meets Thor from the main timeline, and Sylvie's relationship with Thor from her own timeline is never explained in the series.
- “God. Now I understand why Thor found this so annoying.”
- — Loki on Sylvie; The Variant
- Sylvie – “How do I know that, in the final moments, you won't betray me?”
- Loki – “Listen, Sylvie, I... [sighs] I betrayed everyone who ever loved me. I betrayed my father, my brother... my home. I know what I did. And I know why I did it. And that's not who I am anymore.”
- — Journey Into Mystery
Fans began taking an interest in the ship following episode 3 of the Loki series, when the romantic interest between Loki and Sylvie became apparent. Although Thor does not appear as a character in the Loki series, fans began to imagine what a relationship between the three of them would look like. Since all three characters have never interacted together in canon, speculation about their relationship borrows elements from both the canon and fanon relationships between Loki/Thor and Loki/Sylvie. The relationship is depicted both as a family bond and as a romantic one.
The relationship name Sylkior came into usage on social media shortly after Loki episode 3 was released. The term is a combination of the characters names: "Syl" from Sylvie, "ki" from Loki, and "or" from Thor. The emoji set ⚡🐍🗡 (a high voltage bolt, a snake, and a dagger) is used to represent the relationship on social media, notably on Twitter. The high voltage bolt represents Thor, in reference to his powers with lightning; the snake represents Loki when he's in a relationship involving Thor (Loki ships that don't involve Thor use the snowflake emoji ❄ for Loki), in reference to Thor's tale of Loki turning into a snake in their childhood; and the dagger represents Sylvie, in reference to Loki's metaphor on love that he told to Sylvie in response to her question on love. While most of MCU fandom uses ship names involving the concept terms, such as "Thunder" for Thor and "Frost" for Loki (e.g. ThunderFrost = Thor x Loki), such a term has not come into usage among Sylkior shippers.
Many fans speculate that because Loki and Sylvie are two variants of the same being, Thor would embrace Sylvie as a sister. It is unknown if Sylvie had a Thor variant as a sibling in her timeline, but fans speculate that she would embrace Thor in the same way. Some fanworks depict post-Endgame Thor thrilled to have Loki and Sylvie (and sometimes other Loki variants) with him in this manner, since he was deeply traumatized after losing his entire family and now has a family again with Loki and Sylvie. These scenarios are often depicted domestically, with all three recovering and/or healing from their pasts. Sylvie is sometimes depicted as struggling with the role, even if she welcomes it, since she's been alone and on the run for most of her life. Even though Thor and Loki were raised together as siblings, the ship often has a found-family feel to it, as they've been separated from each other (or each others' variants) for a long time, and Sylvie is newly embracing a family. Examples include:
- Fanfic: Wear Your Tragedies by RedactedReader, in which post-Endgame Thor calls Sylvie "sister" and they discuss this and their relationship with Loki
- Fanart: Family portrait by @mjarmerchant
- Fanart: I love them & want them to be a big awkward family by @solidafg
- Fanart: Sibling bonding time by @MysiePereira
- Fanart: Siblings? Siblings by @octisquad
Fans who are interested in Sylkior as a romantic relationship tend to depict Thor and Sylvie embracing each other both as siblings and as lovers. Sylkior shippers often blend canon and fanon dynamics of Loki/Sylvie and Loki/Thor to produce Sylkior. For some, this means integrating Sylvie into the established dynamics of Thorki fanon. This tends to feature a pre-existing relationship between Loki and Thor that Sylvie joins into. For others, it means integrating Thor into the established dynamics of the canon romance between Loki/Sylvie. This relationship is usually depicted as developing after the events of the Loki series, and often include a reunion between Loki and Thor after Loki's death in Avengers: Infinity War. Examples include:
- Fanfic: Two of a Kind and One to Spare by ambiguously, in which Loki takes Sylvie to meet Thor and it turns sexual
- Fanfic: Lost and Sound by snack_size, in which Loki and Sylvie have an initial relationship and bring in Thor
- Fanfic: meet your storm by maharlika, in which Loki and Thor have an initial relationship and bring in Sylvie
In alternate universe scenarios, some fans alter the canon relationships between the characters to produce new character dynamics. This often depicts Sylvie and Loki as individuals who are not alternative variants of the same being, and both naturally exist on the same timeline with Thor. Sometimes Sylvie and Loki are depicted as siblings or even twins, both the children of Laufey. Loki might still be adopted by Odin in this scenario, and so the two are raised separately, and Thor and Loki are still adoptive siblings. Some AUs might have Sylvie as the one adopted as Thor's sibling and raised in Asgard, rather than Loki. Alternatively, Loki and Sylvie are also depicted as being entirely unrelated, but still in the same universe. Examples include:
- Fanfic: take only what you need by tediousTricks (ghostlyAnarchist), in which Thor has an arranged marriage with Sylvie of Jotunheim and Loki is afraid of losing him
- Fanfic: the envy of eden by maharlika, in which Sylvie is Thor's adoptive sibling and they bring in Loki from an omega auction
Sylkior is a relatively new rarepair whose shippers are largely drawn from the much larger Thorki and Sylki fandoms. Because both Thorki and Sylki are regular targets of harassment by antis, many Thorkis and Sylkis who do not ship Sylkior support and defend its shippers when they are harassed.
- Family portrait by @mjarmerchant
- I love them & want them to be a big awkward family by @solidafg
- Sibling bonding time by @MysiePereira
- Siblings? Siblings by @octisquad
- Sylvie meets Thor by @octisquad
- Sleeping by @sensoriumz
- Sylkior in bed (semi-NSFW but not explicit) by @ponderosa121
- Meme "This is my boyfriend Loki, & this is Loki's boyfriend Thor" by @PrettiestThor
- OT3 meme by @feelmynoize
- Love them by @MorgenSevermalt
- Ragnarok Thor won the Sylkior poll! by @moopzies
- Sylkior makeouts by @moopzies
- He is bisexual (他是双性恋呀) by @_Micias_
- Welcome home by @ramenana
- Commission for ponderosa121 by @eliotdrawings
- Another! by lousysharkbutt
- "Wow Loki you were right! Your Thor is indeed hot" by deraniel
- First time the term was used on Twitter appears to be June 23, 2021, which was the day episode 3 Lamentis premiered. Twitter search: sylkior until:2021-06-25 since:2021-06-01. Retrieved October 12, 2021.