Europe of Five Empires

Absolutely not. As a matter of fact, there is no real equivalent of the all-powerful, universal Pope as we know it. There is a Patriarch of Rome, who has the same level of power, influence, and prestige in the Church as various other highest-ranking bishops in the West and the East. Certainly the members of the Pentarchy are his equals, but several other Patriarchs of similar status were set up over time across Christendom (in France, Iberia, Britain, Germany, Scandinavia, the Balkans, Eastern Europe, Northwest Africa, Mesopotamia-Persia, Ethiopia, etc.). ITTL the Western Emperors won a total victory in the power struggle with the Popes, squashing their ambitions for theocratic political autonomy and hegemony within the Church for all time. As a consequence the Church evolved in a decentralized model that allowed Christianity to stay united and the European empires to co-exist within the same Church despite cultural differences and concerns for political autonomy. Much of the power in the Church is in the hands of various regional/'national' Patriarchs and bishops' councils that are subordinate to state authority; ecumenic councils that are co-chaired by the European rulers infrequently act as the supreme authority of the Church to settle doctrinal issues. Thanks to this, the Latin-Greek schism was nipped in the bud and even the Chalcedonian schism was healed once the two sides acknowledged the benefit of reconciliation and cooperation for a common front against Islam; some theological clever thinking 'encouraged' by the secular rulers cleared away the doctrinal misunderstandings. Any equivalent of the Reformation was averted since the Church was not centralized and powerful enough to make it look necessary in the eyes of most Europeans, and they had grown too fond of religious unity of their civilization. As a matter of fact, heretical movements that typically act as a front for radical social reform and anti-taxation claims of the lower classes occasionally and invariably crop up across Christianity, but circumstances have never been favorable enough to their success, so they have been just as invariably and brutally suppressed by the reaction of the state and the elites.

I'm not that good to adjudicate dynastic issues. And 700-850 years of divergence (depending on which PoD we pick) make it rather difficult to identify likely 17th century ruling dynasties for the four empires, nor they make it much likely such dynasties would necessarily be familiar in OTL terms. Even more so since the divergence caused the default European succession system to be different. Parallel evolution in the HRE and the ERE, their combined example, lessened impact of feudalism, and the influence of meritocratic Roman precedent established a succession model that was theoretically elective but in normal circumstances based on appointment of the successor by the incumbent. This was often one of the previous monarch's children, typically the most talented, politically influential, and favored/beloved regardless of order of birth, but not infrequently he could be another trusted member of his family or high noble, minister, or general if the monarch was childless or lacked suitable blood heirs. The case of a monarch ignoring genealogy to pick his preferred successor for reasons of talent, loyalty, political support, or favoritism occurred often enough a strict rule of hereditary succession never developed. Succession by appointment mostly turned out to be a gainful middle ground that avoided the instability and infighting issues of elective monarchy and the genetic accidents and rigidity of hereditary monarchy.

Occasional breakdowns of established succession due to the incumbent and the designated successor dying at the same time did happen, and were settled either by civil war or by election by an assembly of leading men, as circumstances dictated. Successful coups, usurpations, and civil wars also occurred once in a while, but they never were frequent and destructive enough to cause major and lasting harm to the European empires. As a matter of fact, these circumstances caused TTL Europe to develop a notion of divine right of monarchs and aristocracy that was less based on blood than OTL and similar to Chinese 'Mandate of Heaven' in certain ways. A monarch that was appointed or elected in a proper way and rules sufficiently well and fairly is subject to no earthly authority, deriving his right to rule directly by the will of God. Proto-parliamentary bodies typically do exist, but usually in a subordinate or consultative role, and have a real say only in case of major changes to taxation or the fundamental laws of the realm, if any. However, legitimacy of a ruler does not require him to be of royal blood or even noble birth, and in extreme circumstances an incompetent or unjust ruler could be deposed by rebellion. A successful rebellion is interpreted as evidence that divine approval had passed on to the successive ruler or dynasty.

Much the same way, the European elites acknowledge and cherish the notion of an hereditary nobility (ideally confirmed each generation by excellence, duty, and service to the state) but have kept its ranks open to worthy new members. Over time the opportunities of upward social mobility provided by trade, colonization, and military conquest have been relatively common and easy for the talented and the ambitious. Many gifted and lucky commoners have amassed vast riches, risen to high ranks in the army, civil service, or the clergy, or have been ennobled thanks to their wealth, accomplishments in the service of the state as civil or military officials, scholars, or artists, or a successful career managing a business. For the same reasons there is fairly good acceptance of marriages between members of different social classes not too distant in rank and wealth. It goes w/o saying that even w/o this attitude, ITTL European imperial families would be far too few to keep their mating and breeding limited to people of royal blood. Regular intermarriage with members of the high nobility and occasionally the minor nobility and the upper bourgeoisie is the standard.

In this framework, most rulers have been male for the usual reasons, but female monarchs have been frequent and successful enough to be an accepted occurrence. Most often it happens when a monarch lacks suitable male heirs, but has a sufficiently favored, talented, and popular daughter or close female relative whom he trusts more than any other potential alternative, and appoints her as the successor. Alternatively, and just as frequently, it is the case of an Emperor setting up a trusted/beloved, capable, and influential wife as Reigning Empress and co-ruler, and/or de facto regent for a minor child of theirs. Of course it may also be the result of a lady pulling a successful coup. As a matter of fact, an Emperor may often set up his designated successor as co-ruler some time before his death.

Never mind.  Any other questions or comments ?

Well, the LRC and Muscovy are locked into a fratricidal struggle for supremacy since their rise as they understand they need to control the other side and seize the full heritage of Rus to become the equal of the other three empires in power and prestige, but so far their clashes have turned into a stalemate or limited/Phyrric victories, also because of the other empires' meddling to help one side or the other. It seems nobody has yet thought of a peaceful political/dynastic union to settle the dispute, probably b/c of accumulated bad blood and distrust, but it remains a potential option for the future. So does one side somehow seizing a decisive success that breaks the stalemate, or the status quo enduring in the foreseeable future. If and when *Russian reunification would take place, it has the potential to turn stable after a troublesome pacification period, since TTL European culture distrusts and dislikes strict reliance on ethnicity as the groundwork of national identity, and the two sides share the same religion and a broad Slav cultural background. The two states have evolved different Slavic languages for themselves, but it is not anything a sufficiently determined state couldn't change with sufficient time and effort. The other three empires may often pick Rus' division as an excuse to look down on the Slav empires as parvenus of dubious legitimacy, but just as often they may encourage it to keep the Slav states busy and off their own back.

As it concerns the HRE, the ERE, and the NSE, they have no ideological reason for clashing, and they are fairly satisfied with the geopolitical status quo in Europe that took shape with their rise and stabilization, and the victory over Islam. Nonetheless, a certain degree of fierce colonial competition (for territory, trade, and resources) also exists, and it keeps their relations from being too peaceful. Often such competition stays relatively peaceful, occasionally it explodes in colonial wars. Such conflicts are often fought in the colonies, but sometimes they spill over in Europe, and then get fought in the border territories and the sea. This may, and indeed did, cause moderate border changes (certain areas have changed hands various times), but the broad shape of the empires has remained fairly stable for centuries, and these conflicts have caused relatively limited damage to the empires. European culture holds the ideal its empires should always cooperate in brotherly harmony as caretakers of a united 'Western' civilization (that is eventually destined to inherit and rule most or even all of the world, depending on one's opinion of the Asian empires' role in God's plan), and they exist as separate entities out of convenience because of their combined size and complexity. But they live in an imperfect, sinful world, so occasional family squabbles, even fairly bloody and vicious ones, are an inevitable fact of life.  

Europe has not experienced anything of similar destructiveness to the Thirty Years' War since TTL equivalents of the Black Death and the Mongol invasion (names of peoples and leaders may differ, but steppe nomad breakouts are a fairly consistent phenomenon), and the latter only devastated Eastern Europe and the Middle East, and caused the collapse and division of Rus. The European conquest, pacification, and forced assimilation of the Muslim lands was also very brutal for a good while for the usual reasons, but in the end harshness eventually toned down since most North Africans and Middle Easterners in the conquered lands came to realize Islam was a lost cause and accepted conversion to Christianity and cultural assimilation in the HRE or the ERE. The destruction of Mecca and Medina on top of the Europeans conquering almost all the Muslim world was a signal to many God was on the Crusaders' side. The Muslim diehards mostly fled beyond the deserts to the depths of Central Asia or West Africa, where the Crusaders were unwilling or unable to pursue them. Theoretically speaking, the victorious Crusaders planned one day to storm the last Islamic strongholds and finish their bloody job, but such territories seemed remote, difficult to reach, and of relatively limited value, especially in comparison to what they had already conquered or were conquering outside of Europe, so in practice they let them be.

Since the beginning of the Age of Exploration, the European empires have been quite busy colonizing all the areas of the world with valuable resources, a lack of advanced native empires to deter them, and climactic/disease conditions to allow mass European settlement (the Americas, Southern and Eastern Africa, Australasia, and except for mass settlement, Southeast Asia as well). They have already colonized a lot, but it is an half-done job, so the border areas of the colonies in the Americas, Southern and Eastern Africa, Southeast Asia, and Australia are in perpetual state of warfare as the Frontier gradually but relentlessly advances. Things here are not really different from OTL, except the colonizers avoid chattel slavery and genocide for its own racist sake (if a people resists colonization too fiercely, however, they better make their own peace with God). Mass dying off of the Amerindian peoples, however, occurred all the same for the usual reasons.

Relations between the European empires and their Chinese, Indian, and Japanese-Korean counterparts are in practice not very different from the ones between the European empires themselves, despite the extra friction caused by religious and cultural differences. That is, often peaceful relations, sometimes friendly, sometimes tense, in a background of fierce trade competition, interrupted by occasional armed clashes and bouts of colonial warfare. As a rule, the Europeans may fight to seize favorable trade terms, coastal bases, and privileged access to economic resources, rather than extensive territorial acquisitions or control of the Asian empires at large. The European empires get the upper hand most of the time, but the Asian empires are sufficiently strong and solid to avoid complete subordination or direct colonization. An element of genuine respect also plays put in relative European restraint, since India and East Asia are the only cultures and empires most Europeans are driven to regard as their true peers in the world.

The Europeans apply more or less the same 'indirect colonization' strategy to the areas (West and Central Africa) they are unable to penetrate and settle because of climate and disease, out of necessity. As a rule their attitude here would be as brutal as in the Americas, since native African polities are much weaker and less solid in comparison to colonizers than the Asian empires, and the Europeans regard the African and Amerindian cultures as barbarian and devoid of value, but they are unable to make much inroads in these regions, so they make themselves content with seizing and exploiting what they can, peacefully trading when they must or is simply the convenient thing to do. On the other hand, the Europeans avoided the adoption of chattel slavery in the colonies, so Africa has been spared the onslaught of transatlantic slave trade.

Potential unity of the Slav lands is not that much of a serious concern for the other three empires, especially for the HRE and the ERE since they would always be able to withstand a united Russia-Ukraine on their own. It is a bit more serious for the NSE since it might then become the weakest side in a conflict with Rus and the weakest member of the European quartet, but not by that much (especially once they properly develop their Brazilian colonies). So they meddle in the LRE-Muscovy conflict, support one side or the other to reap concessions elsewhere or keep the two states and off their back.The status quo has its advantages, but it's not like a Slav re-unification would be seen as an existential challenge or a dire threat to the balance of power by the other empires (although it might make the NSE more than a bit anxious). Given their broad sense of geopolitical propriety, they may easily treat it as a natural, inevitable occurrence (kinda like many OTL Europeans saw German and Italian unification).

Broadly speaking, if we substitute Poland with Ukraine as the dominant nationality, the LRC is a fairly close geopolitical and cultural equivalent of the PLC. Because of the superior strength of the HRE and the ERE, its core lies in the Dniepr basin, with a secondary one in the Donets basin. The main reason for its rise was the steppe nomad invasion wrecking and splitting Kievan Rus and allowing Western-Central Ukraine and Muscovy-Russian heartland to rise as independent and rival centers of power of similar strength (both a bit more developed than OTL since TTL Europe developed a larger and more robust continental trade network earlier). I honestly cannot tell for sure if the LRC developed anything similar to the domestic instability problems of its OTL counterpart. It might go both ways, since the Slav lands are still one of the least developed and advanced parts of Europe just like OTL, but on the other hand TTL Europe as a whole is more developed and centralized, and feudalism left a significantly lessened imprint. In the end I assume the LRC is probably more solid than the PLC. What is sure is the LRC is almost entirely focused on the Rus lands, barring occasional attempts to cpntest control of the eastern Baltic to the NSE. Muscovy does the same, and in addition is focused on colonial expansion in northern Asia. Neither polity seriously attempts to contest control of Eastern Europe to the HRE and the ERE, b/c these empires are much stronger and have politically and culturally assimilated West and South Slavs.

No, I would assume the OTL PLC dysfunctional degree of aristocratic anarchy with a figurehead monarch does not exist, or they would have fallen to their stronger neighbors long ago. In that state, I doubt they would have been able to resist Russian pressure for too long, since ITTL Muscovy does not have the major distraction of recurring conflicts with an hostile Ottoman Empire. TTL European empires share the existence of proto-parliamentary bodies to balance the power of the emperors to some varying degree, usually ranging from a consultative role to having an important say when major changes to taxation or legislation have to take place. The emperors usually control the bulk of executive power, the army, and the bureaucracy, and have a significant ability to legislate by degree; in no case they are figureheads. I'd say the pendulum swings from strong autocracy to some proto-parliamentary power-sharing between the ruler and the rest of the elites (nobility, bureaucracy, clergy, professional army, bourgeoisie), at different times and in different states.

 As usual, the model they attempt to follow is Rome, which has precedents for both in the Dominate and the Principate. Admittedly, it provides a strong precedent for the Republic too, but it is still a bit too early for that to get mainstream support (give it another 2-4 generations for the social and technological base of modern democracy to build up). As a matter of fact, a few attempts occurred over time to swing the pendulum all the way to (de facto) oligarchic republics, but all of them have eventually failed. Such vast, complex states work much better with a strong, unitary executive, and this too is a lesson of the Classical past TTL European political theory is fond of remembering.