History

 Kara is the second-in-command of the Dísir, Bor's valkyrior. At one point in the past, the leader of the Disir, Brün started a rebellion against Bor and her valkyrior including Kara started feeding on other Asgardian Gods. When Bor discovered what the Disir were up to, he cast them out of all the realms, to exist in the spaces in spirit alone. They were cursed to remain forever hungry and feed only on the spirits of Asgardian Gods, for they would only be in Asgard or Hel and out of the Disir's reach. 
 

Siege of Asgard

Ages later, Loki had surmised a plan with Norman Osborn, the director of Hammer and leader of the Dark Avengers to invade Asgard. Before the Siege on Asgard, Loki summoned them in Latveria. He managed to get Brun and her Disir to submit to him. He made a deal with Hela, who no longer had her own realm that he would give her a realm if she would spare his soul. After she agreed, Loki showed Mephisto the power of the Disir and gave them to the dark lord in exchange for giving Hela a portion of his realm. The deal was made, Mephisto gave a portion of his kingdom for Hela to govern for a thousand and one years in exchange for the Disir's service to Mephisto for a hundred and one days. During the Siege, Brun led the Disir to Asgard and attempted to devour the souls of the fallen Asgardians but Hela had sent Danielle Moonstar, a former mutant who had owed her a favor to guide the fallen Asgardians to Hela's realm as a Valkyrie. 
 

Post Siege

Kara and her fellow Disir have become warriors of Mephisto and do his bidding. Mephisto had grown a fondness for Brun, who plotted to give herself and all of her fellow Disir to him if he would allow them to invade Valhalla and feed on the fallen Asgardians. When Mephisto agreed to let them invade Valhalla,