Thunderwar

Thunderwar is the het ship between Thor and Sif from the Marvel Cinematic Universe and Marvel comic fandoms.

Thor
Sif is the goddess of war and childhood friend of Thor. Thanks to Thor, who believed in her capabilities, she became one of the most appreciated warriors of Asgard, along with the Warriors Three and the Thunder God himself. Along with Loki and the Warriors Three, Sif is convinced by Thor to attack Jotunheim, in response of an attempt by some Frost Giants to steal the Casket of Ancient Winters. While in Jotunheim, Sif fights alongside with her friends against an army of Giants led by Laufey himself, and manages to slain many of them, but is forced to flee when they're outnumbered. Eventually, the team is saved by Odin, who intervenes to prevent their killing. Helpless, Sif assists Thor's banishment on Earth. Some days later, Sif persuades the Warriors Three to ask Odin to recall Thor back home, but when they arrive in the throne room, they find Loki sitting as the new ruler of Asgard, as a substitute to Odin who's fallen into Odinsleep. Loki denies their request to call his stepbrother back, but they decide to ignore his order and to go to Midgard anyway.

Heimdall agrees with them and opens Bifrost Bridge for them, and the four Gods arrive on Earth, in New Mexico. Here, they easily spot Thor, and find out that he's been tricked by Loki's lies. Briefly later, The Destroyer is sent to Earth by Loki to kill Thor and the other Asgardians, and Sif engages it in battle with her friends. While the Warriors Three bought her some time, Sif jumped from a rooftop onto its back attacking the The Destroyer from above, piercing its chest with her sword in its staff-like form. Immediately after, however, the Destroyer regenerated itself and almost killed Sif with an energy blast shot from its eye. Sif flees with her companions, leaving Thor, who claims to have a plan, behind, but only to assist his sacrifice and his rebirth in his divine form. Back in Asgard, Sif brings Heimdall to the Restore Room, while Thor fights, and eventually defeats, Loki. Along with other Asgardians, Sif celebrates Odin's return to the throne and Thor's return in the realm, participating in a gargantuan banquet.

Thor: The Dark World
After Odin used dark energy to send Thor to Earth to retrieve Loki and the Tesseract, Sif informed Heimdall that the Allfather was weak but under Eir's care. She then asked about Thor and Heimdall informed her that Thor survived the journey. Sif was present when Thor returned to Asgard with Loki and the Tesseract. She was also present when Thor rallied his fellow Asgardians, informing them that they were to protect the Nine Realms from the Marauders. After the Battle of New York, Sif was battling in Vanaheim when Thor arrived, despite her claims she was in control. After Thor quelled the events, Sif had noticed Thor had become distracted as of late. It was shown Sif has feelings for Thor, but he was unable to reciprocate them because his heart belonged to Jane Foster. When Jane arrived on Asgard, Sif glared at her, clearly jealous of her, but nonetheless helped Thor escape with her to the Dark World with Loki. She was presumably charged with treason because of her involvement, but released due to Thor's action on Earth. After the conflict Sif and Volstagg gave the Aether to the Collector.

Avengers: Infinity War
Either during the above or the attack by Thanos on the remaining Asgardian civilsation, Sif is killed.

In of the Marvel animation universe, during Thor and Sif's youths as Thor trains and makes a public sceptical of them, Sif grows tired of Thor not taking it seriously than he should, since his opponents let him win. Before Sif leaves to join the Valkyries, Thor finds her in the barn getting her horse ready as he asks Sif why she missed his victory. Sif tells Thor the honest true about his victories and how he'll be worthy to join most celebrated warriors in Asgard, the Einherjar. This angers Thor as he refuses to believe her. Sif tries to tell Thor that she does believe in him when he asked Sif why she has little faith in him, but Thor wasn't happy with her answer as he challenges Sif to prove himself but ends up losing to a pitch fork wielding Sif. Before Sif leaves Asgard, as Loki tells Sif that Thor is wrong about her not fitting in with the Valkyries, she asks Loki to stop protecting his brother with his praises as they are doing his older brother no favors. Thor watches Sif disappear into the air, before he drags Loki into his plan to prove himself.

During Sif's archery training, Brunhilde notices that her mind is on a certain male that she left behind on Asgard, and tells her to forget the male she wishes to get away from if she truly wants to join the sisterhood. After Thor found the Elderstahl in Jotunheim and needed to return home with the others, he knew that they'll need Sif's help, but Loki asks Thor if it is her who he wishes to see or the horses that she might provide them with. Just has Sif was getting ready to take a dip in one of the pools, Thor approaches Sif to ask her for help but Sif wouldn't listen to Thor as she had left Asgard to get away from him and he should leave before he is found by the Valkyries. Thor explains the terrible events that happened in Jotunheim and how he needs to return home to ensure that Sword of Surtur isn't used again as he shows the said sword to her. Before Sif could give Thor her answer, a group of Valkyries find the two together and take Thor prisoner beside his male friends, apart from Loki.

Brunhilde wishes for Thor's death but Sif wishes the opposite and when the Frost Giants attacked, Sif frees Thor from his cuffs so they could join the battle together but Brunhilde sends them away, and asks Sif to return once she is truly ready as she can tell that Sif still cares for Thor. When Algrim finds the young warriors and takes the sword from them, Sif assists Thor in his take to clam it back from the Dark Elf and to aid Asgard in their battle with the Forest Giants. Once the battle was won and peace returned to Asgard, Thor finds Sif in the barn again as he asks Sif about her being recruited into the new Einherjar. Sif ask Thor about it since she has a feeling that he had something to do with it, but Thor claims that Sif proving herself in battle is what got her in, and he is glad that it wasn't just a mere woman who had beaten him with the barn tool. Thor's choice of words made him sound like that he wishes to have a rematch with Sif as she asks him about it to be sure, before they began their rematch Thor pulls Sif into a kiss.

Children
Torunn Thorsdóttir Torunn Thorsdóttir is the daughter of the Marvel comic versions of Thor and Sif, from the  universe and timelines,, (comics) and  (animation). Like her father's weapon, Torunn wields a magical sword that has similar abilities to Thor's mighty hammer. To help their daughter reach her true potential as a true hero, as he once done, and knew that none of the Warriors in Asgard can help Torunn, Thor leaves their daughter in the care of the Avengers so they can teach her the very same lesson that Odin wanted him to learn long ago. When Torunn finally learnt that lesson and was given a chance to be with her parents again in Asgard, she tells her father that her home is on Earth with her adoptive family who raised her, Thor understands this and gives Torunn Asgardian armour before sending her back to Earth. In both the Earth-10071 and Earth-10943 universes, however, Thor and Sif are both dead, making their daughter a orphan beside the other children of the original Avengers, while in the Earth-555326 universe Thor and Sif are alive.

Fanon
Thunderwar has support from the Marvel Earth universes that have Thor and Sif as a couple. Some see the animated Thor: Tales of Asgard film as a Thunderwar film, due to the moments that are shared between young Thor x Sif.

Some comics fans are bothered by the fact that MCU didn't really attempt to give a nod to their romantic relationship in the comics. They take a pity on Sif because they think Sif truly loves and cares for Thor. The fans mention Sif as more than what Thor deserves as she is more beautiful and tougher compared to some women around him. They also note the way Odin approves Sif to be Thor's partner.

On AO3, Thunderwar is the sixth most written ship for Thor and the second most written for Sif.

Fandom
FAN FICTION
 * Thor/Sif (Thor films) on FanFiction.net
 * Thor/Sif (Avengers cartoon) on FanFiction.net
 * Thor/Sif (Thor comics) on FanFiction.net
 * Thor/Sif (Thor comics) on FanFiction.net

TUMBLR

Trivia

 * In Norse mythology, Thor and Sif, on which these characters are based, are married