Haakon Iron-Fist is former Stormcloak who committed atrocities at Karthwasten during Ulfric’s campaign to retake Markarth from the Forsworn. The massacre itself is hinted at during the quest Season Unending. Haakon’s lack of contrition and defiance of his superiors resulted in him being imprisoned, mostly due to the politics of the time. As Ulfric had yet to kill Torygg and announce his rebellion, Haakon implies an acquittal would have raised suspicions of a possible insurrection by the Stormcloaks. However, his personal pride would not allow him to apologize for his behavior or serve under a man who asked him to.