Forgive me, this may have been brought up prior in the thread, but why is Soissons a king-level title in the first place? Under Aegidius it was run a bit more properly Roman-like, but I thought Penny MacGeorge demonstrated fairly well that under Syagrius the whole enterprise devolved into little more than a warlord's fiefdom, best illustrated by the domain-ending Battle of Soissons in 486-- a proper state can at least scramble for successors and maintain some administration when a battle is lost, have pretenders flee abroad, have a bureaucracy, etc., but when a warlord starts to lose, his domain disintegrates rapidly.
Now, I recognize that Soissons was often called a kingdom, but it's also entirely possible to grant any title any other title's tier with a simple "name_tier = [count/duke/king/emperor]" line in the appropriate entry in landed_titles. Given how quickly Soissons fell, I would advocate making Syagrius holder of a ducal-level Soissons that merely is named a kingdom in landed_titles. A ducal Soissons would disintegrate more rapidly, better reflect the challenges of just keeping such a state together with what meager administrative power Syagrius had at his disposal, and this could all be done using mechanics already in CK2 and so would not have to rely on special events or CBs for the Franks to beat the crap out of it, if that's how the AI chose to roll. A proper king-level Kingdom of Soissons (titular) could serve as an update if Syagrius just survives the initial deluge, if it's felt necessary.
Well bear in mind that in Late Antiquity/Early Middle Ages there are many different levels of authority. In the West, particularly in Gaul, there are
civitas (main city and surrounding territory or 'county') authorities who were called
comes. These officials somewhat inelegantly became the basis for the later Carolingian and beyond 'counts' that make up the base unit of political authority in a CK2 game. In Southern Gaul at this time more
civitases were run by city
curiales, but in Northern Gaul where the military hegemony was the strongest authority around,
comes prevailed over
curiales. (In other words, to be completely realistic, most territories south of the Loire and major surviving cities north of it should be Grand Mayorships in a CK2 game set in 500, not Counties, with the exception of Trier where a local
comes seems to have been stationed.
Above them we have the local
dux, collectively known as the
duces. This is a bit more fungible, as in some places in Gaul
comes answered directly to a
dux and in some places
comes or
curiales answered directly to the Gallic Prefecture (occassionally re-established throughout our period) or, even more often, to a local
rex or
reges. These 'petty' kings were effectively
dux-level authorities with greater power - either more territory (multiple
dux level holdings?) or, in Syagrius' case, a very large army (larger than that commanded by a normal
dux - Aegidius and Syagrius's 'kingdom' fended off both the Visigoths and the Franks once or twice before the end). Each of Clovis' sons was a petty king, but by the next power-sharing division two generations later each Merovingian
reges was a proper 'great' king, some of whom styled themselves
imperator as well.
So what is a petty-king, really, in the authority heirarchy? Well, CK2 doesn't have a rung for this, but in the 5th century the Roman commander north of the Loire was usually titled
magister militum of the army of Northern Gaul, the former army of the Rhine (though much reduced in size - no longer anything like 4 legions strong, maybe half that.) In late Antiquity a
magister militum definitely outranks the local
duces, but is he really a 'great king' the way that Clovis was after his conquests of the Alamanni, the other Franks, and the Visigoths? The Way Theodoric was? No. Aegidius' power was pretty definitely constrained between the Loire and the Rhine, even before the death of Majorian, and only decreased after that. It's also telling that once he cut himself off from the Imperial authorities in Italy, Aegidius seems to have lost the 'authority' to control Northern Gaul - Arbogast does not appear to function as a subordinate of Aegidius or Syagrius, and the Romano-British Amoricans seem to have only titularly acknowledged Aegidius and Syagrius because they couldn't really defend themselves, while Childeric, a former
magister militum of the same army Aegidius commanded, seems to have taken his removal from said army personally, and tried (and failed) to get it back after Aegidius declared himself independent from Italy.
So Aegidius and Syagrius? Well, Aegidius died before our period begins, but if we were starting in 460 I would give him
dux level authority over the vanilla duchies of Anjou, Orleans, Champagne, Normandy, Valois, Upper Loraine, Lower Loraine, Alsace, Luxemburg, and Koln. This would leave Childeric and Clovis, prior to 460, with Flanders, Holland, and Brabant. By 480, however, Syagrius' authority had dwindled. It still seemed nessecary for Clovis to destroy Syagrius before he could securely take Paris, though, so I would leave Syagrius with
dux level authority over the territories between the Franks and Paris: Valois, Normandy, Orleans, Anjou, and Champagne. He could be given the titular title 'King of the Romans' (which could be expanded so that anyone sufficiently Romanized (Gallo-Roman or Romano-Frank) could claim it for themselves (Arbogast, Paul) or be the 'Petty King' of Soissons.
Bear in mind that there are several holes in the Penny MacGeorge theory: one, it assumes that Aegidius and Syagrius went through the trouble of setting up an actual basis for legitimate Kingship. We have no evidence to support this. The Franks knew Syagrius as 'King of the Romans,' but they may have just called him that because their own leaders were called Kings and Syagrius' position was sort of unquantified after Aegidius's succession from Italy and subsequent death. Or Syagrius may have looked around him and seen his Frankish, Visigothic, and Burgundian rivals calling themselves 'king' and decided he needed some sort of official title. But in either case, there's no archaeological evidence that Syagrius ever did anything to establish the foundation of a legitimate kingship. He and his father seem to have continued to operate north of the Loire the way they had always done - as a field army with ultimate authority (backed by a combination of Roman Imperial authority and Roman arms before Aegidius went independant, and by arms alone afterwards) but without a developed civilian infrastructure that legitimated Syagrius' control over the North of Gaul. In other words, whereas the Frankish Kings had spent generations building up a civilian infrastructure and power basis and alliances with Gallo-Romans and Romano-Germans in the Rhineland prior to 460, and the Visigoths and Burgundians had been handed a Roman civilian infrastructure in Aquitaine and Burgundy to 'serve' as protection for, and then later became rulers of, Aegidius and Syagrius were making it all up on the fly.
That doesn't mean, however, that his authority wasn't recognized by northern Gallo-Roman elites and non-elites, however. One thing that the last 30 years of Late Antique research is in agreement on is that the Gallo-Romans, even those north of the Loire, preferred Roman authorities and Roman officials whenever they could find them. When they couldn't, the usually picted the most-Roman local aristocrat and elevated him to some level of local authority: in the early 5th century this took the form of imperial usurpers (when an army was backing them) or 'Bagaudae' uprisings (which Late Antique scholars have proven were not peasants fighting to return to a non-Roman way of life but local Roman elites backed by local Roman populaces trying to establish Roman authority in the absence of strong imperial control, and being maligned by the increasingly paranoid Roman elites in Southern Gaul and Italy for doing so). In the late 5th century this took the form of petty-kingships like Aegdius and Syagrius', or Arbogast's control over Trier (although no one seems to have called him that.) In all cases, the local, very-Roman and want-to-stay-Roman-thank-you populace of Gaul, up to the Rhine, looked around for the most Roman authority they could find, and made them their leader, in order to survive the period. In the lower Rhineland, the most Roman authority around WAS Childeric, who had been a Roman
magister militum and who is described as a pretty cultured Roman himself. His ethnic background may have been 'Frank', but by now the Franks of the Rhineland were about as Roman as the Romans of Northern Gaul, the only difference was that for the Romans of the area being a soldier was still a paid proffession you worked at full time: for the Franks it was primarily a thing you did when you weren't farming (which explains why the Franks usually lost against Roman soldiers). The major exception to this were the Romano-Frankish offers, like Childeric, who came from a long, century or more tradition of Frankish elites becoming Romanized enough to be seen as 'Roman' by other Romans, regardless of their background. Now, there were Franks to the East of the Upper Rhine who were less Roman, and notably in Trier it wasn't a local Frankish King who became the first person the local Romans turned to when the Empire lost control in the north, but a Romano-Frankish
comes of the Rhineland Franks, the most Romanized of the Frankish peoples.
In North-Central, Gaul, however, the most Roman authority around was undoubtably Aegidius, and after him his son, Syagrius. They came from Gallo-Roman roots, and even if their authority didn't come with deep civilian administrative infrastructural roots, they don't seem to have faced any opposition from Gallo-Romans within whatever territory they defended, and Late Antique scholars are pretty convinced that the fued between Syagrius and Clovis was more of a rivalry between opposing Roman commanders than a 'barbarian' king conquering the 'last Roman' in the North.
Additionally, to again counter the theory Penny MacGeorge theory, plenty of Northern Gallic kingdoms seem to have gone out with a particularly big bang in the late 5th century and early 6th. Most of Clovis' conquests took the form of one big battle - against other Frankish Kings, against Alamannic Kings, against Syagrius, even against the Visigoths, who were unarguably the most developed and entrenched realm in Gaul at the time of their defeat. If not for Theodoric, the Visigoths would have completely lost their Gallic holdings in the wake of the battle of Vouille. And even though the Visigoths did come up with an heir to the throne, the same could not be said of Clovis' defeated Frankish rival Kings or his defeated Alamannic Kings. In the late 5th century it seems to be the rule that if your kingdom was barely more than a few days' ride in either direction, one big battle could undo you completely.
Finally, remember that Childeric was the former
magister militum of the same army Aegidius and Syagrius commanded. This means that the armies' soldiers and officers would probably have known Clovis about as well as they knew Syagrius. When Clovis
beat Syagrius, therefore, it would only be natural for those soldiers to fall under the command of the son of their former commander. He was about as Roman as anyone else in the North, and probably a good deal more Roman than his Frankish and Alamannic rivalries - why put forth another candidate when clearly the most obvious heir to command of the army of Northern Gaul was the guy who just beat your former commander?
