damn thats why i hate flashbacks.
first 3 chapters, the story starts to run but then BAM 2 fladhbacks chapters completely throw the storyline out of its rails.
for those wondering why he killed that dude, my guess would be that a) probably an assasin send to kill him, so he had no chance to survice instead of killing him or b) more unlikly but not impossible the person heavily insulted either the pope or his father (since he shouldnt care about any other person (...maybe also his step sister)) to the point were his concept of honor couldnt let him live.