By season three, Haesten had become one of the victims of the witch Skade (Thea Sofie Lock Naess), who captivated him with her charm.
His character changed in season four, as he started to reveal he was ready to give up war and settle down with a wife and some land.
He had one last opportunity to kill Uhtred, having captured him and his friends on the road, but he let it slip when he wandered off into the forest, resulting in Eadith (Stefanie Martini) cutting the protagonists down and freeing them.
Fans were shocked when Haesten actually tried to help Eadith at the end of season four, showing some sort of compassion towards her.
He was last seen fleeing the Winchester siege on his own, as Eadith had refused to go with him. His character is most likely based on the real Viking chieftain – Hastein.