Thunderwar

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

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.

Fandom
FAN FICTION
 * Thor/Sif tag on FanFiction.net
 * Thor/Sif tag on FanFiction.net

TUMBLR

Trivia

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