I'm not too excited about the season 2 sneak peak, mostly because it's one out-of-context scene and I'll believe it when I actually see it in the show, alright.
Also, you know, just cause you were on each side of a battle doesn't necessarily make you enemies. I mean, I've been reading some of the stories of the Skjöldungar and one of those stories is the Battle of Bråvalla, which was basically two great Viking kings (one of them Sigurd Ring, the father of one Ragnar Lothbrok) agreeing to meet in battle to allow one of them - the old king Harald Hildetand - a chance to die in battle. They weren't enemies, they just - anyway, the historians are pretty sure that battle never actually happened, though it says something about the whole Valhalla belief system if there is even a core of truth.
Also, you know, just cause you were on each side of a battle doesn't necessarily make you enemies. I mean, I've been reading some of the stories of the Skjöldungar and one of those stories is the Battle of Bråvalla, which was basically two great Viking kings (one of them Sigurd Ring, the father of one Ragnar Lothbrok) agreeing to meet in battle to allow one of them - the old king Harald Hildetand - a chance to die in battle. They weren't enemies, they just - anyway, the historians are pretty sure that battle never actually happened, though it says something about the whole Valhalla belief system if there is even a core of truth.