Why Arya Stark and Beric Dondarrion are frenemies on Game of Thrones

Spoilers ahead for Game of Thrones, season 8, episode 2, “A Knight of the Seven Kingdoms.”
“A Knight of the Seven Kingdoms,” the second episode of Game of Thrones’ final season, is crammed with fireside chats and cold reunions, including one between Arya Stark and two men she traveled with in earlier seasons: the Hound and Beric Dondarrion. It’s a meeting heavy with unspoken emotions coming from bad memories. Beric tells Arya, “My lady, it’s good