Atreus/Shiro
I killed a god. I shouldn't have, I was young - he'd made me angry, I thought I could do anything I wanted because I'd just found out who my father was. It was wrong, I was wrong.
But it was part of a series of events that lead to Ragnarok. Without that, things might have gone differently. Baldur was still after us, but this involved Thor, too, since it was his son.