The trait line and scripts for rebellions against the current kind are great, I love the bit about "not getting on any boats, my lord!"
Anyway, I'm currently playing a HRE campaign and having a blast. Despite my emperor starting out with Offends the Nobles, and Inspires Civil War, which led to all of my generals picking a side, I've managed to expend in central Europe by picking on excommunicated factions. I conquered much of France and Genoa and actually have gained reputation up to "Very Reliable" and nearly max Pope faction points. (Instigating a land-grab, I mean a crusade against Paris helped)
Anyway, I was wondering if the emperor of HRE, Heinrich, always starts out as offending the nobles. I actually had families split apart and my faction heir actually rebel. Some guys got traits like "Family was traitorous" and "kingmaker". One quirk though, was that a guy was in rebel mode and hadn't yet turned into a brigand, and by some crazy luck became faction heir right before my current king died. So for one turn, the king was a rebel!