Yea i think Frederick II was under guardianship by that time, i ment Heinrich VI, i am not sure how much power he would habe in relation to the pope, but i think after the road to canossa, the emperors and the pope had a bad relation and the papacy constantly tried to curtail the power of the emperors, especially in Italy, they did not want to be boxed in, either you need a very very decisive victory over the catholic church, like the french once did when they established the avignion papacy or it will be almost impossible for the staufers to break papal power without civil war. Keep in mind all these princes of the empire are just waiting for a sign of weakness. However, before the interregnum the position of emperor was way stronger then later down the line so the staufers still have a shot at establishing their rule. I think the most realistic outcome would be 2 Hohenstaufer Branches, one beign based in southern italy with Frederick II and his descendans (who loved italy, grew up there partly and saw himself just as much if not more as a italian rather then a german king) and one branch of Staufers in Swabia with people like Philipp II. Who would hold the emperor titel ? I am really not sure, but without the interregnum the empire as a whole would develope completely different. I think a mighty Staufer Dynastie in the southwest would always be a power factor, essentially they would become something like early Habsburgs but with a more Germany (and/or italy) focus. I dont think to be honest that any sane emperor would move the capital officialy to Milan, as that would mean disgruntling ALL the german princes and making room for potential rivals. They would always need to travel and be present atleast somewhat. I know that during the early HRE days there were characters who wanted to rule from rome but i think nothing became of that. Not sure if Frederick II and his descendands would have what it takes but who knows ? So all in all, i think it would come down to having two branches, One based in swabia, possibly with control of some of Arles and Burgundy and one beign based in Sicily and maybe with aspirations for Jerusalem. Both of them could be emperor tho it would make more sense for the german branch. The interregnum and alot of powerloss for the emperor would not happen and i think the staufers could have a shot to establish their rule with the erbreichsplan (maybe giving up italian aspirations and just ruling them personaly not as part of the empire to pacify the pope) also the staufers would have a good base inside the empire even if they loose the throne they would still be big shots and a uniting factor of the region. One thing that i think could MAYBE happen later down the line is, that you have a split towards a northern and southern realm. Also as a side note, there were aspirations in the city of Mainz to become a rival to rome and appoint an antipope, it was only stopped due to bad luck more or less, but i dont know that much about this, might be interesting. here a link: https://en.wikipedia.org/wiki/Conrad_of_Wittelsbach and https://en.wikipedia.org/wiki/Christian_I_(archbishop_of_Mainz)This is a very interesting scenario. Though wasn't Frederick II under Papal guardianship at the time? Do you think the Pope would relinquish custody of him, or would he hope to raise him in Sicily to have a loyal puppet or at least a sympathetic ally on the Imperial Throne. If say Frederick II and the Papacy were to collaborate again, how much real tangible power do you think the Hohenstaufen dynasty could effectively wield with players like Philippe II Augustus being next door? Do you see the HRE perhaps in the future moving the Captal to Milan since its the crossroads between Italy and Germany?
Do you recommendations on sources about Medieval Germany and the reign of Frederick II?