There has been much speculation on the imperial coronation of Charlemagne in 800 and the sources written on it hold vary varying opinions as to which of the parties involved in this coronation played the key role in making it happen. These characters consist of; The Pope, the court (namely Alucin) and Charlemagne himself. It can also be disputed that the coronation was simply a natural outcome of the long term growth in Frankish and Papal relations over time.
Our initial response to this question would be that the person gaining the power was surely the one that had to take the necessarry steps in order to get it. However, it has been disputed that Charlemagne didn't have much motivation to become Holy Roman Emperor and so he wouldn't have put a great deal of effort into the process or pushed for it, further still some sources argue that Charles did not even want the position. C. Delise Burns argues that Charles wanted the role beause of its “connection[...] with Christian Rome”. Even so, this is not very strong evidence for the amount of effort Charles would have had to put into becoming emperor, had it been him in charge of the movement. The position of Holy Roman Emperor did not entitle him to much more power, even the new rights, F. Lot says that he made “very limited use [of] his new imperial dignity” after the coronation, which is true, as he continued to use his old Royal seal even after becoming Emperor. This could be percieved as showing a disregard for Roman customs, Henri Fichtenau even suggests that he sought to “undermine the spiritual supremacy of Byzantium.” This points us in a direction that suggests that Charles may have simply 'went with it' (M. Costamberys claims that Charlemagne had “passed from the conception of a Roman Empire to that of a Frankish Empire”) in order to heighten his power over the Byzantines by taking their highest position so that no one else could take it, making the Frankish crown