Karlsson is a Swedish Pikeman and one of the Heroes in With Fire & Sword. He likes Priest Spasokukotsky, dislikes Algirdas and Tepes, is liked by Fatima, is disliked by Oksana and Victor De La Buscador, and disapproves of heavy losses, unpaid wages and starvation. He also dislikes fighting his own people as he says after telling his story, but is not confirmed if he will say anything if you are fighting the Swedish. Due to his high polearm skill, he is good as a pikeman or lancer, especially with the Hussar Lance. He identifies religiously as Lutheran, as noted in-game when he explains why he likes Priest Spasokukotsky.