The Latin Empire was a diverse place; linguistically, it held Frenchmen (mostly Flemish), Greeks, Turks, and Bulgarians, though most nobility only spoke French and Greek- and the latter was mostly among the clergy. It was home to a wide array of religious sects as well- Catholicism, of course, was the state religion and the one espoused by the clergy, but Sunni Islam was, of course, relevant in Anatolia and Syria, and Orthodox Christianity, the Greek rite, remained in the countrysides of the Balkans, and there were scattered Jewish communities throughout the crusader empire. The administration was mostly flemish and greek, but in the east, Arabic also saw use. Emperor Baldwin II was personally of the opinion that attempting to force certain languages on the common folk would simply cause confusion and clutter the administration. As a result, he mandated that while laws would be written in French or greek (the languages he knew) they would be translated before being imposed. While hardly a revolution, many scholars believe it was the first step in standardizing the dialect of French that the Latin Empire used; mass translation into multiple languages (Greek, Arabic, and whatever other local dialect,) with a few alphabets, from a central location, necessitated everyone know how to read and write comprehensively.
While the Patriarch of Constantinople was held under strict regulation, he was still allowed to operate. However, by now, the Metropolitan of Athens was becoming the major religious official of the region. The current Metropolitan of Athens was Guy du Atens, and worked with the recently obtained Diocese of Aleppo, which followed the Syrian Rite, but was still beholden to the Papacy. However, with the Latin Empire able to establish holdings in areas of Christendom that weren’t often under Roman power, this led to the Papacy attempting to rectify some of the disputes between the two rites. Regardless of theological matters, Emperor Baldwin did not really do much with the Church if he could help it- he would attend church every week, of course, and provide money for functions, but he was not a zealous man by nature. Though, like any sane claimant to Roman glory, he did make efforts to push that he held Antioch, Jerusalem, and Constantinople itself.
The century since the conquest of the Eastern Roman Empire had led to some notable conversions. Thrace was now estimated, by a slim majority, to be majority Roman catholic, as was Thessaloniki. Similarly, the Aegean Sea was mostly Catholicized due to the bloody nature of the conquests and their low population. Despite this, however, outside of major cities, most people retained Orthodox views. Anatolia was perhaps the most contentious area- it was still a battleground between the Orthodox Christians and Sunni Muslims even before the introduction of catholic conversion efforts. The most religiously stable part of the empire, ironically, was Syria, whose southern regions remained under a Muslim governor due to Baldwin’s promise in the crusade.
With the decline of Constantinople’s patriarch, other groups began to exert more autonomy. Kiev and Ras were the primary examples of this; Kiev already had disputes with the city’s doctrine, and the Patriarch eventually declared complete independence. In Serbia, however, there were opportunities for secular powers as well. Serbia began to take on traditionally Greek trappings, clearly seeking to establish itself as a successor to the Eastern Empire. This eventually led to Serbian King Stefan Milutin waging a second war with the Bulgarians. This war was a resounding success, laying siege to Tyrnovo, the Bulgarian capital. However, while it was an unabashed war of conquest, Serbia did not wish to draw too much attention from the usurping Latins.
However, the Golden Horde, nominal overlord of the Rus principalities, had largely been successful in efforts to snuff out their independence and autonomy- and this included Kiev. However, this mainly mattered in political matters- at the time, little effort was made on religious change. However, the golden horde was still allied to the Empire of Trebizond, which would prove quite sufficient, at least for a time. The main goal of the alliance was preventing war, and Emperor Baldwin was not a warmaker by nature and did not want to explore the option while other choices remained.
However, this peace faltered rather quickly. In 1312, a rebellion broke out in Egypt against the Ilkhan Öljaitü before spreading into Iraq. While Öljaitü was not an overly zealous man, he had placed a Christian in charge of the provinces of Egypt and northern Iraq. This Egyptian rebellion, led by a former slave who had been assistant to a Mongol officer. As a result of this, he was able to take Cairo and amass a following, breaking the Mongol hold on the provinces. It was shortly after this that Iraq’s own peasants declared for the Egyptians. While this situation would normally be put down easily enough, the Golden Horde saw an opportunity to reclaim Azerbaijan and invaded. With no other choice, the Persian empire called in Constantinople, which triggered the alliances with Trebizond, and, through them, Serbia.
Baldwin decided to focus on Serbia and Trebizond first but did order Syria to help the Ilkhanate. This would prove a mistake, as, during the campaign into Serbia (deemed the greater threat to the Balkans), Baldwin was slain. The empire fell to the twelve-year-old Constantine and a council of nobility. The nobility proved to be rather poor commanders, and after two years of humiliating defeat after defeat (the nobility suffered from infighting, and few of them wanted to reinforce each other's armies), surrendered to the Serbians. The Serbians gleefully took much of Epirus and declared the Serbian Empire. The regency council, headed by Alexander of Antioch, did have much better luck against Trebizond and were able to take much of the western coast during the long and protracted war. While the empire was able to keep Trebizond off of the Ilkhanate, it was difficult without coordinated leadership, and with no noble clearly more powerful than the others bar Thessaloniki, which had suffered grossly at the Serbian hand, coordinated leadership was a pipe dream. Constantine, for his part, did a great deal of studying when he was able to. This, and his nobles losing what was his personal land, gave him ideas. He already had a professional navy- one of the only ones in the Mediterranean. Why not a permanent army? He had most of Greece regardless of the losses in Epirus. The problem was the nobility despised the notion, and with the conquests in Anatolia, many were expanding their power. One even went so far as to go over Constantine's head and directly get the pope to declare him Duke of Antalya! This was the first feudal fief in the Anatolian holdings in quite a while; since their reconquest, they had been the either direct property of the Emperor or had been under non-hereditary governors. That settled it- Constantine was going to destroy Trebizond, and established his hold on his empire, one way or another.
As soon as the emperor turned 15, he demanded an army under his command. The nobles had been able to sideline him before, but now that he had full command of his provinces, this was no longer the case. He took out several loans from Venetian and Genoese bankers, amassed a new, personal army, and set off into Anatolia. He moved like lightning. Trebizond’s armies were slow to respond, having to cross back into Anatolia through Iraq, or hostile Syria. As a result, in three years, Constantine’s armies were able to spread far into Anatolia. As Constantine had no intention of letting there be an Empire of Trebizond after this war, he established numerous governors who all understood plain as day that they answered directly to him. Not his nobility, not the church, not the peasants, and not the merchants. Him. Emperor Constantine. Naturally, this upset his nobility, (and the fact that many of his governors were cousins of the established ones would come back to harm the young emperor,) but the fact the young emperor had the largest army and was currently the most successful commander in the empire made challenging him seem very very stupid. And so they didn’t. On the battlefield anyway. But they attempted to get the mercenaries to betray him, or switch to their contract, which wouldn’t seem like a betrayal on the surface until it was too late. Unfortunately, the Emperor had foreseen this and had paid significant premiums that his lesser nobility, of which only a few of whom had significant land to challenge the emperor (even with Epirus lost,) were not quite able to match.
After about eight months of the campaign, the Emperor met a Trebizond army, who were in similar condition but far smaller numbers. It was a massacre. Constantine seemed insistent on cutting down every single soldier. It was after this, the Battle of Ankara, that Constantine earned his most famous epithet; Constantine Répandre du Sang- Constantine the Blood Spiller. It was a name the emperor would go on to earn again and again in his conquest of Trebizond. Over the next year, the Ilkhanate would call out again and again for the, clearly capable, emperor’s help, but Constantine would rebuke them. In his mind, they had already lost, Egypt and the Golden Horde would prove too much for them, he was simply using them as an opportunity to conquer a fierce rival. When the Emperor reached Sinope, however, he found Trebizondian and Golden Horde forces amassing a fortification ready for him. While Constantine would lay siege briefly, he was not a patient young man (scarcely more than the boy he had been when he launched his gruesome campaign,) and his mercenaries were contract workers, meaning that he could scarcely waste time with them. As a result, just before winter, he ordered an assault. While he would be able to take the city, it was costly in lives, material, and in paying the mercenaries afterward. However, he had bankrupted Trebizond, and soon his naval commander brought him news that even their holding in Crimea had been seized. With the depletion of their army, the defeat of their navy, and the fall of one of their most important cities, the Empire of Trebizond was forced to yield to whatever Constantine demanded. When he declared that he would take the whole of their empire, but spare the nobility who accepted his suzerainty and converted to catholicism, this was naturally contested by the emperor. However, Constantine’s declaration that nobles who surrendered would retain their privileges and land won over just enough to topple Trebizond and hand him dominion over Anatolia.
However, it was too late for the Ilkhans. The baring down of the horde and the mass revolts meant they had to make peace. Egypt was assured independence under the Hassen dynasty, forming a powerful new sultanate. The Golden horde, of course, made its caucasian inroads, and the Persian core of the empire was radically destabilized after four years of war with powerful neighbors and an enraged native population. The court naturally detested Constantine, seeing him as a bloodthirsty opportunist. They were right of course, but it still hurt. Regardless, Constantine himself enjoyed quite the popularity with the people, pushing his victories abroad as culling an eastern threat and establishing that he was truly a Roman Emperor. Constantine would use this, and the fact that he owned most of the land he had taken, to start developing one of the first standing armies of the era. It would be expensive, of course, and require finding people who were… mostly willing to sign up for the profession, but that would all be arranged. And of course, when it was done, he knew exactly who he would turn the first generation of his new legion on.