Take it from someone who read the manga.
This isn't your average revenge story. though it may seem like that at first it really is not. it's so much better. The revenge part was needed for thorfinn character to grow into a whiny lil shit to a lovable man. I've never had this much connection nor praise such character since I've met guts and miyamoto musashi from berserk and vagabond and both of those series are masterpieces. You won't hate a character. There's no character to hate except the main prontagonist but only in the early stage. you'll love him. You will love his growth. From the weak child to an adult young man.
The Anime is slow so I've read the manga first then watched the anime. I must say. Most of the time when I read the manga first I tend to get bored of the anime but this is one of those rare instances where you read the manga and wanna watch the anime despite knowing what will happen next.
