elsa might be the rezero character of all time. she shows up as the villain of the first arc and she keeps being important to the story even after her death in the 4th. everywhere you look there she is. but shes not even, like, "important" as far as lore and history goes. shes not a witch or archbishop or anything, shes just a really cunty assassin who keeps being relevant somehow. haunting the narrative without even being that significant in the grand scheme of things
but i like that she mattered. it wouldve been really obvious to just have her be a throwaway obstacle for arcs 1+4 (just to have continuity) but she wasnt that! she was a person, someone who had a history, who knew people, whos life and death would cause somekind of affect on the world around her. its stuff like that, that makes the world of the story feel real, like theres always a lot of moving pieces. not just npcs and the main character