The Emperor of the Keltoi (Known as the Oljawalosalv by the Keltoi), was the most important political, economic, and military leader in the Keltoic Empire. While the decentralization of the Keltoi severally limited any Emperor's ability to rule, they still had a massive amount of influence over their nation. For example, a given Emperor could set taxes, raise armies, and even depose of Chieftains. Even trade had a lot of oversight from the Emperor - every merchant who wished to trade in the entity of the Empire or any of the major cities needed permission from the Emperor. However, despite their theoretical unilateral power, the Emperorship was often reduced to a turf war between the Emperor and his Chieftains or the Senate. This would make the Keltoic Emperor one of the weaker European monarchs, despite the powerful nation behind him.
In theory, the Emperor was the most powerful member of the Keltoic government. And while it is true that he was the most powerful individually, other groups could give him a run for his money. For example, if enough Chieftains were aligned against the Emperor, little could be done but bow to them, or at least. When the Senate was rebellious, it could usually be dealt with more harshly, but that group still exerted quite a bit of control over the Emperor. Ultimately, the Emperor could exert a lot of power over his domain, but was always limited by other groups.
Like most Monarchies, the Keltoi had a system in which the Emperor was seceded by one of his relatives. However, unlike other systems, where the rules where fixed as to who would gain the throne, Each Emperor would produce his own list. Generally, the list would be about 10 names long, ordered from his most preferred to least preferred successor. Should someone on the list die, the list would be edited to stay up to date While technically the only rule for the list was that the people on it had to be male, in practice the Emperors generally only put close relatives in line to secede them. For the most part, this was a solid system - it was very had to press a claim to the throne against someone who the Emperor preferred, and it wasn't until the 7th century that he Keltoi began to have problems on that front.
Influence and Powers
While his power was unavoidably checked by the Chieftains and Seante, the Emperor still wielded substantial influence. For example, he could allow or disallow merchants from other nations access to Keltoia. While Chieftains could give merchants access to their own Chiefdoms, these charters could be overruled by the Emperor, and were relatively rare. This leverage in trade also gave the Emperor close to a monopoly on foreign issues. While these were rare for most of Keltoia's history, there were very few checks to prevent the Emperor from doing as he wished in that Realm. In addition, he and the senate worked together to set national taxes, and in practice, the Emperor had the final say in what the taxes were.
Another power of the Emperor was his ability to pass laws, with the consent of the senate. However, in practice, this could effectively be shorted to "The Emperor could pass laws." Whenever the senate put up serious resistance, they triggered terrible backlash from the Emperor. For example, the Emperor could seize their assets, kick them out of the senate, and even cull their ranks on occasion. The last major power the Emperor had was control over the military. While the chiefdoms were responsible for defending themselves, any major war effort had to be lead by the Emperor. This was pretty rare - the Keltoi were by and large peaceful - but when it did happen, the Emperor was more or less able to rule the nation unilaterally, something that rarely happened otherwise.