As noted, Korath was originally introduced in GotG (2014), where he was seen working as muscle for Ronan, who served as the film's primary antagonist. Thanks to Drax, he dies in this film too. GotG is, therefore, no help in bridging this gap.
Also as noted, he later shows up in Captain Marvel set about 20 years earlier. This film is also no help — and apparently, a lot has changed between the two time periods.
Korath was originally introduced in 2014’s Guardians of the Galaxy, where he was seen working as muscle for Ronan, who served as the film’s primary antagonist. While Korath met his demise at the hands of Drax the Destroyer in this film, he later reappeared in 2019’s Captain Marvel, which was set around 20 years prior to Guardians. His appearance in Captain Marvel revealed Korath’s role in the Kree military unit, Starforce, before he served Ronan. However, over the course of these two appearances, Korath’s character received little exploration and he spent most his time relegated to the role of stony-faced muscle for larger villains. That all changes in What If…?.
Korath’s introduction in “What If… T’Challa Became a Star-Lord” mirrors his original introduction in Guardians of the Galaxy. Like Peter Quill in the opening to Guardians, T’Challa is seen breaking into the Temple of the Power Stone on the planet Morag. When he takes the orb containing the Power Stone, Korath arrives, holding him at gunpoint and demanding to know his identity. However, whereas Quill’s introduction as “Star-Lord” was met with bewilderment from Korath, when T’Challa unmasks, the Kree enforcer immediately begins singing his praises. Not only has Korath heard of this version of Star-Lord, he’s a fan. The result is an outpouring of emotion and sincerity never before seen in any of Korath’s live-action appearances.
News Concerns, What If Gives Korath More Personality Than He Ever Had In Movies
Unfortunately, What If…? is no help either, as it picks up at the same point as GotG.
To confirm, his official story briefing between his appearances has not been fully detailed. It may yet be in a future work.
Any hints in Ronan’s appearances, since he’s associated with Korath in the same films?
The version seen in Captain Marvel is the leader of the Accusers and has yet to embrace the bloody markings he wears in GotG that earned him the title of a zealot. However, while his appearance in the film is also interesting, it also does nothing to detail his future fate as a zealot in partnership with Thanos & leading Korath as his henchman.
At the time this question was posted, we’re no closer to knowing what happens in between.