The last survivor of an elite Asgardian unit that was wiped out in one afternoon, who spent the centuries afterwards drinking on a garbage planet.
Valkyrie is the only member of her order left alive. The rest died in a single engagement against Hela, and the film shows it once, in slow motion, and then never lets her talk about it. When we meet her she is calling herself Scrapper 142, selling captured fighters on Sakaar, and drinking.
Tessa Thompson plays the recovery without ever making it a lesson. By Endgame she is running a refugee town in Norway, and by Love and Thunder she has the worst part of the job, which is the meetings.