Colleen McCullough was a well-respected mainstream novelist (The Thornbirds), with a background in neurology, and a personal interest in Roman history. I found out about her on a Reddit thread when I was looking up terms for Roman military commanders for my in-progress book on Spinoza.
McCullough seems to have been mainly trying to make sense of the late Republican period and the transition to the Imperial model. Some things in the secondary sources didn't make total sense to her, so she resorted to the primary sources, and reasoning. She used the idea that everything happens for a reason to infer events not explicitly recorded, when they were the best explanation for the historical record. The sorts of inferences she permitted herself include reasoning backwards from their words and actions about the likely character, motives, and unobserved circumstances of the people involved. For instance, she infers from Marius's occasional incapacitating fits, and changed, erratic behavior late in life, that he suffered a series of strokes. And she infers from the signs of an unlikely friendship between Marius and Sulla, connections between Sulla and the Dictator Julius Caesar, and some extant marriage records, that Marius and Sulla married into the Julius Caesar family and thus became friends. She also considered the possibility that the record could be distorted, so long as that was consistent with the motives, circumstances, and characters producing that record. For instance, she has to alter the date of one of Cicero's speeches for the purposes of her story, but permits herself to do so because it was a speech that would have been embarrassing for Cicero, but less so if its date were misrecorded, so he had a motive to get the date wrong.
Masters of Rome is her attempt to lay out what she thinks actually happened, in the form of a series of historical novels. And while the series has some literary flaws*, especially in the first book, it's also by far the best vampire story I've encountered.
More precisely, it seems like an attempt at a realistic, historically accurate account of the kinds of people and events that very obviously would have inspired a vampire myth.
There are little touches like tracking that a legion is more powerful once it's been "blooded" - but I'm going to focus on the blood-politics of the central players: the Roman Patrician elite.
When we first encounter Sulla, he's extremely pale, aristocratic, very fond of drama, with a nonreproductive sexual orientation, important because he's got very old blood but on the outs because he's from an impoverished branch, living off the substance of women captivated by his glamor, desperately craving for validation, and showing signs of predatory excitement at a bloody public animal sacrifice. He builds up a sense of entitled resentment at the existing power structure, gradually physically deteriorates into a highly photosensitive mildly disfigured monster, and late in life gets himself elected Dictator indefinitely, kills off a bunch of his political enemies, and then retires to his villa where he releases the accumulated pressure of following the rules by putting on an orgiastic party until he dies in an explosion of blood.
During his dictatorship, Sulla also rationalized the Roman civil administration and courts, eliminating various sorts of overlapping jurisdiction that are the result of a long, unevenly planned Republican history, turning things into something more like the apparatus of a rationally planned centralized state.
Marius starts out more like a normal healthy provincial man (but discouraged from a political career because he hasn't got old blood), but as he faces escalating bad-faith aristocratic opposition during the progression of his career, builds up some sort of spiritual charge, which gets released near the end of his life as he marches on Rome and kills a bunch of his enemies. I am not sure this perfectly matches the vampire image - he's not quite a zombie either - but it seems to fit broadly into some sort of undead schema.
Marius's career advanced as a response to the failure of the Roman Republic's military system.
The Roman Republic was originally constituted as a mutual defense arrangement among the initial Roman landowners and their heirs, the Patrician families. Military service was an obligation the stakeholders owed to each other. The initial event that destabilized this arrangement was the extension of permission to live in Rome, to foreigners who were granted full economic and residency rights, but not citizenship. These became the Plebeians of Rome. Presumably the idea was that it's a Pareto improvement - a win-in, a mutually beneficial trade - for existing stakeholders to allow immigration that doesn't dilute their voting power. But as they came to regard Rome as their home over generations, Plebeians grew to resent unaccountable Patrician exercise of power over them, and eventually staged a series of walkouts - some of the earliest recorded general strikes - that resulted in important concessions of political power.
First, the laws were written down, replacing the prior regime where Patricians could beat Plebeians with the Fasces whenever they thought or felt the Plebeian was violating an unwritten rule (i.e. whenever they felt entitled to). Eventually, the Plebeians forced the Patricians to create a new political office, of the Tribunes of the Plebs - elected officials whose persons were sacrosanct (it was sacrilege to physically attack them), and who had the power of the veto - any Plebeian Tribune individually had the power to block any action of government.
However, the old families still had a significant coordination advantage - they knew each other and how the system worked, they passed along through generations know-how relevant to the administration of the Roman state and religion, and they preferentially helped each other (thus constituting a dominant clique). Moreover, membership in the Patrician-dominated Senate was a mimetic desire target. What constituted an upwardly mobile Plebeian? One who was on their way to acceptance by the existing ruling clique!
Membership in the Senate was open to the Plebs, but with a positive requirement of significant land ownership, and a prohibition against economic activity not based on land ownership, which meant that new members had incentives substantively similar to those of the ruling clique. Eventually, there were recognized old Plebeian families which, while eligible for Plebeian rather than Patrician political offices, were basically treated like minor Patricians - their blood was old, so they were allowed power and presumed loyal to the clique.
As some cities near the Mediterranean began to concentrate power by conquering or otherwise dominating others, Rome was one of the winners - eventually it ruled all of Italy. But the number of stakeholders participating in governance did not expand proportionally to the resources under Rome's control - so eventually, the escalation in the scale of wars concomitant to increasing concentration of power threatened to exhaust the capacity of the Republican system to produce soldiers.
At first, the strains were economic - part of a landowning citizen's duty to participate in shared defense was a duty to provide their own equipment and serve without meaningful compensation for the cost of their time. But this meant that huge wars such as those Rome fought against Carthage could economically ruin the small landholders who constituted the majority of the soldiery, but didn't have access to the political offices the members of the ruling clique could use to enrich themselves at the expense of the foreign territory Rome controlled. Roman elites also benefited from the ability to rent and farm for profit the vast tracts of publicly acquired land - "latifundia" - at subsidized rates.
A generation or two before Marius and Sulla, the brothers Gracchi were Tribunes of the Plebs who attempted a land redistribution in order to effectively reenfranchise Roman citizens. This redistribution was sufficiently popular among the Roman electorate - but disliked by the ruling clique - that the ruling clique resorted to assassinations to prevent the Gracchi from carrying out their program.
This gives us an upper bound on the coordination capacity of the ruling clique. It was clever and coordinated enough to hold onto power and slap down individual challengers despite a nominally weak political position, but not farsighted and wise enough to redesign the Roman constitution to realign incentives under new circumstances.
We need this context to explain the extraordinary careers of Marius and Sulla. They lived in a generation shortly after that of the Gracchi, in which generalship among the ruling clique was lacking, because both Rome's recent military victories and the extreme wealth inequality they benefited from had alleviated short-run performance pressure, in favor of cliquishness and skill at abusing political privilege to enrich one's family and supporters. This led to a series of military defeats that not only allowed Marius to demonstrate his competence by outperforming the men he succeeded, but eventually killed off enough of Rome's fighting-age citizens eligible for military service, to constitute a real emergency. Marius responded by changing a core element of Rome's constitution: he replaced the old model of a group of citizens mutually obliged to participate in shared defence, with a professional model. Soldiers were a sort of labor commodity, paid, equipped, and trained at state expense. The Roman state was their customer.
But Marius went further; to extract better service from the soldiers than a purely transactional model might allow, he reformed Roman military idolatry to effectively establish a new religion; each legion bore a silver eagle that represented it as a single corporate person in service to the idea of Rome.
Taken naively within the context of the old regime, this seems like a win-win, much like the admission of the Plebeians, or the reforms of the Gracchi. But also like the admission of the Plebeians, it constituted a destabilizing factor that would eventually radically alter the nature of the Roman regime. Marius's reforms began a process of military rationalization that culminated with the establishment by Augustus of a standing army with a fixed term of service and standardized retirement benefits. Considered as a whole, this transition from the model of army as the obligation of key stakeholders, to army as a professional service, added an important element to the Roman constitution: the army itself. In the Republic, the army was something the Romans did - in the Empire, the army was a distinct, permanent institution with permanent members loyal to it, bound to the civilian governance structure only through a sort of military religion that justified its acts of violence in terms of service to the idea of Rome, of which the physical city was a sort of embodiment, something like a temple city. For a comparison, consider the status of the city of Asshur in the Assyrian empire, ruled for most practical purposes from Nineveh, but still pointing to Asshur and its eponymous god as its ultimate source of legitimacy.
So, the constraints on the professional army were that it had limited capacity to coordinate to innovate its own religion or legitimating story. It could, though, and eventually did, act sporadically through individual opportunists to extract concessions from political decisionmakers in Rome, which eventually meant that a large share of Roman tax revenues went to bribing the army, and the Emperor - who was functionally the dictator of Rome - was frequently chosen on the basis of the respect of the soldiery. In short, a conscious, persistent community of common interest defined by owning land in the environs of the city of Rome was replaced in large part with a less conscious, intermittent community of common interest defined by participation in the "Roman" army.
The conservative aristocrats of Marius's time were not so articulate as this in their opposition to Marius's reforms. While the ruling clique had a coordination advantage over outsiders, it did not have such a large advantage as a good-faith deliberative body has over a mob. This brings me back to the subject of vampires.
While the body of Roman law grew to be extensive, from the point of view of the ruling clique legal procedures and codes were never the core of Roman governance, but sometimes a concession to the plebs (who could sometimes even coordinate to insist the laws be enforced), and sometimes a convenient apparatus for implementing the intentions of the true governance structure. The Roman constitution defines various executive roles, occupied at any given time by an individual - and for the principal roles, that individual would most usually be a member of one of the old families of Rome.
Roman naming conventions and family law both support the impression that the true identities involved in Roman politics are not the identities of individual human organisms, but the immortal lineages to which they belong.
As far as family law is concerned, the father's power of life and death over his household - including adult sons - makes every familiar patriarch and his patrilineal descendants a single political unit.
Most striking on the surface is the three-part naming convention. The first name was one's personal name, and effectively served to disambiguate siblings; generally there were family traditions of first names - e.g. naming the first one Gaius, the second Sextus, etc. The second name was the primary family name, passed down patrilineally - Caesar, Cornelius, Pompeius, Metellus, etc. And after this were surnames, originally descriptive nicknames, which sometimes came to be passed down patrilineally even when inapplicable. For instance, Caesar means a full head of hair, but some of the Caesars were balding. Others could be earned during one's lifetime, like Pompeius Magnus, "Pompey the Great," or Scipio Africanus, who got the name "Africanus" for his successful military campaign in Africa. This is illustrated in McCullough's book in many cases, but to greatest effect with the Julius family. In the first novel, and elderly Gaius Julius Caesar introduces Marius and Sulla and backs their political careers. His eldest son is another Gaius Julius Caesar, and his grandson is the famous dictator Gaius Julius Caesar. Even when one remembers that these are distinct people, the sharing of names necessarily causes the persons sharing the name to be mentally associated more closely than they otherwise might.
But most importantly, the assumptions and expectations of elite Roman culture backed this up. Men were expected to have some ambitions for themselves, but primarily to carry on a family legacy. Political offices were often informally reserved for a given family - certain families had a tradition of serving as Pontifex or Augur, for instance, and certain families were expected to move upwards through the series of executive offices known as the cursus honorum. Rules would be bent or broken - preferably covertly - among the ruling clique, in order to preserve these customs.
In addition to specific familial traditions and entitlements, there was a loose but essential ranking of prestige, by one's family's degree of acculturation into the ethos of the ruling clique. Best was to have old Patrician blood traceable back to the founding of Rome or earlier. Next best was to come from an old Plebeian family which had become integrated with the Roman aristocracy over many generations - the logic of this preference is that such people could be trusted to behave as cliquishly as the Patricians. This was in part because Roman Patricians and their traditional institutions like the Senate were considered extremely prestigious in Rome. If a citizen outside the ruling clique was up-and-coming, and sensitive to the system of approval around them, they probably wanted very much for their family to join the Roman Senate, and become eligible for the cursus honorum. This gave the ruling clique psychic influence over the new entrant, since they would naturally be eager to win the clique's approval, and thus consent to be conditioned and acculturated into that clique. Thus, when there was need for new talent, or individuals outside the clique grew powerful enough to present a potential challenge, the newcomer would in most cases be turned into another traditional aristocratic family - albeit in the first few generations, one with too much new blood to be trusted with the highest offices.
Marius was a very unusual person to succeed in Roman politics because he did not even grown up in Rome, but a nearby city. He was legally a Roman citizen, but his family had not been acculturated into Roman aristocratic mores. While he wanted the acceptance of the Roman elite, he didn't implicitly identify with them, so they felt - correctly - that they couldn't trust him to act in the interests of Rome's true governing regime. The fact that they let him seek political office anyway testifies to their desperation as the military situation deteriorated - and later to his robust popularity.
Sulla was narratively more similar to the sort of person traditionally favored - from a disgraced branch of the Cornelius Sulla family, he was sufficiently old-blooded for some Romans to be willing to overlook his untraditional, theatrical acculturation. While Marius seized power in Rome near the end of his life by making use of the new institution he'd built, the professional army, his authority to kill his enemies was not formally validated by the Senate. Sulla, on the other hand, was formally given the office of Dictator - and seems to have sincerely intended to use his power conservatively, to reinstate and bolster the old regime.
Turning rising stars into aristocrats was not the only way Rome brought new blood under the influence of the old families. Since Roman executives felt free to make unprincipled exceptions for other members of the ruling clique, a citizen could only get so far appealing to formal legal rights and procedures. If they were at all ambitious, they would try to establish a patronage relationship with one of the old families that could get exceptions made. In this relationship, the member of an old family was called a patron, and the outsider brought under the patron's protection was called a client. When feasible, clients would assemble at their patron's front door every morning, both to ask favors (patrons traditionally gave their clients an allowance) and to await instructions, in case their patron needed to mobilize their clients for some political task. While the local resource flows in this relationship went from the patron to the client, the aggregate effect was to bolster elite Romans' advantage at accessing political office, since they could count on their clients' support, while new men with no insider status had no clients, since they were in no position to do political favors. The profit from the customary abuse of political office - as well as ordinary elite privileges like access to the latifundia - paid for the elites' gifts to clients. So far from clients profiting at patrons' expense, patrons and clients together profited at the expense of the politically unprotected.
The supremacy of loyalty over procedure even extended to outright bribery, at least according to McCullough - there appears to have been an effective norm not against taking bribes, but against disloyalty to whoever bribed you.
The patron-client relationship informally subordinated a nominally free person to a member of the governing elite, but there was of course a legible, extreme version recognized explicitly under Roman law: slavery. Surviving documents like the Bible and the Code of Hammurabi attest to slavery as a highly regulated institution in Asia Minor; punishments for a master injuring a slave were different than those for a slave injuring his master, but both actions were bounded by state-enforced penalties. By contrast, Roman slavery was closer to absolute - a slave was private property, which the owner had the right not only to use properly, but also to abuse or destroy at his discretion. And while the written laws might recognize a Roman citizen with no slaves as legally equal to any other citizen, under the informal norms of prestige, owning no slaves made you a man of no consequence, marked you as living in abject poverty. So - in McCullough's account - Sulla endured considerable hardships early in life in order retain ownership of the bare minimum property required for decency - one slave.
What's the common thread of the landownership requirements and proscription of commercial activities for members in the Senatorial and Equestrian class, the importance of the patron-client relationship, and the sense that a man living decently owned another person? This gets at the true constitution of the Roman Republic's ruling Aristocratic clique: they understood themselves to be a republic of territorial dominators - what economists call "stationary bandits." Aristocratic families had a common interest in supporting each others' ability to exercise independent control of their respective territories, and ability to extract resources from the people and things within that territory.
While the version of this political order specifically located in Rome ended with Augustus's institutionalization of the Imperial system, its specifically aristocratic operating protocols persisted in some form even after the rise of Christianity, the Vandal conquests of Iberia and Africa, and the concomitant collapse of the Western Roman Empire's tax base. Plot points from McCullough's novels will be familiar to anyone who had played the feudalism simulator Crusader Kings. While officially the law recognized the personhood of everyone who lived in Christendom, in practice the function of most people was a sort of economic livestock that enhanced the productivity of various land claims. Much like Roman Equestrians and Senators were defined in large part by their possession of Roman lands, Feudal lords were defined by their claims to different sections of the old Roman tax base. They preferentially married and collaborated with other families with long aristocratic histories. Lesser lords were frequently subordinated to greater ones, and the liege-vassal relation can be seen as a formalization of patronage; persons who taxed no other persons were not even vassals, but mere subjects. And while Feudal lords frequently contended for control of territory, conspired, seduced, fabricated claims over territory, and even fought outright battles to decide whose claim was legitimate, this was all within a framework where only the Lords really mattered - peasant rebellions were uniformly suppressed.
The main difference between the Republican and Medieval aristocracies, however, was formal recognition of the right of a Lord to maintain a private army. This eventually led to an escalation of the scale of military competition. During the Republican era, this transformed independent city-states into amalgamated empires, which occasionally and begrudgingly promoted outsiders with merit like Marius. And during the Medieval era, this led to the emergence of modern states, with large functional hierarchies that promoted any individual, regardless of his ancestry - as Napoleon famously said - on the basis of merit.
Possibly the last holdouts of the old regime of competing extractive aristocratic landowners were the English Cavaliers who founded the Southern colonies of the United States. The American Civil War established a sort of Modern closure; what remained of the old aristocratic elites was for the most part a vague, covert corrupting force which - while frequently still in possession of disproportionate, concentrated wealth - existed within the context of modern states nominally opposed to its existence.
One final note: A careful reader will have noticed that I've told this story almost entirely from the perspective of the Patricians and their allies. There's another story to be told, at least as important, from the perspective of the Plebeians. But until recently they had few or no historians to document their perspective, so their legible allies are remembered, perhaps libelously, as demagogues like the orator Demosthenes, or as madmen like the emperor Caligula. But I thought the Aristocratic story worth rationalizing as well, since the aristocrats tend to assume their own perspective so thoroughly that they can't be bothered to try to make it intelligible to an outsider, but they instead assume that the idea of what the "best" people are is already shared.
Perhaps we can now better understand the vampires' side of the story.
* The series starts off a little rough in terms of style. The writing is a bit on-the-nose. She brags about her erudition and precision in leaving some terms like dignitas untranslated because the Latin word doesn't exactly map onto our cognate "dignity" - why not instead use the English word, but point out that the Roman idea of dignity is somewhat different from ours? One of the pleasures of reading about people in foreign times and places is learning to rearrange one's own ideas and definitions, in order to make sense of a foreign perspective. Practicing this sort of flexibility can lead to rearranging ideas better in one's native language - and none of the statements about "dignitas" would have been at all difficult to make sense of, if they instead talked about "dignity." All that would have been much more forgivable if she had also been careful not to use anachronistic terms that refer etymologically to events that took place and ideas that were developed much later. Combined with the dialogue's contemporary slangy feel, I got the sense that McCullough hadn't bothered trying to think about subtle but important differences in rhythm and tone between ancient Latin and contemporary English speakers, but was instead trying to figure out which contemporary sorts of Anglophones would explain the events of the story (a flaw she shares with at least the BBC version of I, Claudius), with the occasional graft of an important Latin idea. All these problems become milder as the series goes on, perhaps because she became more comfortable with the very ambitious sort of intercultural historical interpolation she was attempting.