There were two factors which helped Charles Martel, who himself was not a legitimate son of Pepin of Herstal. Because Pepin's son died shortly before he died himself, he did not leave a legitimate heir and his grandson was too young still. The Moors from Spain tried to take advantage of the power vacuum and Charles Martel swiftly defended the Western part of the Empire. When he was afterwards requested to come to Byzantium though he did not follow the call of the Emperor. Charles Martel though did never become a king himself, but as Majordomo acted as such when he divided up the kingdom after his death in two parts for his sons Carloman and Pepin to become Majordomo for Austrasia and Neustria.
These two sons effectively laid down the distribution of spiritual and worldly powers, which became the pillars for the Western Roman Catholic empire. Most of their lives the two sons worked together effectively and as such we only can assume that there is more to Carloman becoming a monk at Monte Cassino and leaving the Frankish empire to be unified by Pepin. Carloman was instrumental in subduing the Lombards in Northern Italy, who remained faithful to the Byzantine Empire and its Patriarch in Ravenna.
Hence both had to be eliminated and hence it was Carloman who factually established the area from Ravenna to Naples with Rome at its centre as domain in which the Roman Catholic Church could be established. As such Carloman left the Frankish empire to be unified by Pepin and received back the 'donation of Pepin', later fraudulently called the 'donation of Constantin'.
In doing so a centuries long struggle was initiated as to who was the real power in the Catholic Empire, the worldly power or the spiritual one. Emperor or Pope. But neither was still there in the modern sense and although 'Pope' Gregor is regarded as the transition pope between the Byzantine empire and the new Frankish empire of course Gregor could not have been pope in the sense that later Roman Catholic Popes were. But since the whole process was initiated by Charles Martel we have to assume that the Pepin family very well knew what they were doing.
Which leaves an interesting figure in between 'pope' Gregor and Pope Stephen. 'Pope' Zacharias after all was a Greek.
There exists an interesting legend:
"Ethelbert, King of Mercia and general monarch, sent to Charles Martel, the Right Worshipful Grand Master of France (father of King Pepin), who had been educated by Nimus Graecus, he sent over from France (about A.D. 710) some expert Masons to teach the Saxons those laws and usages of the ancient fraternity, that had been happily preserved from the havoc of the Goths"
According to Pritchard "one Carolus Marcil in France, was taught the art of Masonry by Mannon Grecus".
Was then the predecessor of Stephen then perhaps Mannon Graecus? In that case the real first pope was Stephen and he was only later associated to be of the Bobone family, which later became the Orsini family. Bobone and Pepin is not a far stretch and neither is Pepin and Stephen. In that case it was his own brother Carloman who anointed Pepin the Short as king of France.
It may very well be that at the end of their lives the classic struggle between Pope and King set in and Pepin imprisoned his brother in Vienna, who still honours the fact in the Vienna Cathedral St. Stephen.
And so Stephen (Carloman) became the first Martyr of the newly established Roman Catholic Church.