I like to think at some point in time there must have been a lot of local lords, technically owing feilty to the Roman Empire, who decided to declare themselves sovereign and independent of the formerly great Rome; traitors, rebels, whatever you would call them.
Who were some of the first to do this? Were they considered naive and treasonous? Were the first to do so just waiting to be crushed by the empire? Or was this simply considered the "prudent" reaction to something fairly significant? My general understanding of the fall of Rome was that there was no clearly defined date... so what finally convinced some of the europeans out there to say "Forget Rome, I'm in charge now".
Was former status in the Empire given any consideration here? Were the lords all descendant from Roman appointed rulers/administrators?
Or was the whole place in such disarray with warfare and Germanic invasions that the notion of a "traitorous Roman subject" becomes silly?
All of the breakway Sub-Roman kingdoms that emerged in the late Fifth Century were created by powerful Northern European army leaders (~and kings, but not in the way we understand that term today; more like warlords) who either conquered their territory out of existing Roman provinces (like the Vandals in North Africa) or expanded their Imperially sanctioned territory beyond its original limits (like the Visigoths in Spain and Southern Gaul) seized administrative control of the provinces where their armies had been garrisoned (like the Burgundians and Odoacer in Italy) or made alliances with regional Roman aristocrats who agreed to support the new regime because the Empire could no longer field armies to defend them (The Franks in Northern France.) No Roman aristocrats or officers attempted to make themselves kings. One Roman General in North Western Gaul (Aegidius) and his son, who succeeded him, is sometimes anachronisticaly styled by non-historians as a sort of 'king' based on much later writing (Gregory of Tours) that refers to him as the 'rex romanorum' in some places, but in other places he is called a usurper, 'tyrannis', or even an Emperor, 'princepem romanorum'. It seems much more in keeping with Roman psychology regarding the idea of monarchy to suggest that once he stopped recognizing the authority of the Ravenna court (which at the time was under the control of non-Roman warlords) he might have assumed some quasi-Imperial title for himself, and there's even some evidence that he might have pledged allegiance to the Eastern Roman Emperor, Leo, but no real reason to assume he tried to set up an independent personal kingdom in North Western Gaul.
Now, the legend of 'Arthur' may hint that one or more Roman aristocrats of the post-Roman former province of Britain may have made themselves warlord-kings of a sort, and there is even some vague hints from the historical evidence to suggest that the man we know as 'Aurelius Ambrosius' may have done just that. There is one solid reference to a 'King Riothamus' who may be the actual historical root of the Arthur legend, who in the mid-late 400s seems to have brought many of the Romano-British people and any remaining soldiers on the island across the channel to Brittany, where they established an alliance with the Imperial court in Ravenna and attempted to assist the Emperor Anthemius of the Western Empire in containing the advance of the Visigoths, but they were ambushed and overwhelmed and we never hear of him again. But Britain had been abandoned by the Empire since with early 400s, so I'm not sure it really counts as a Roman aristocrat overthrowing local imperial authority.