So, some of ya may know about Stefan Dusan, first ruler of the Serbian empire, amazing general and all around a hyper competent man. Apparently during his intervention of the Roman civil war of 1341-47, there was some talk of crowning him Roman Emperor.
So, what if that happened and he was crowned Roman Emperor? Interestingly enough, with the exception of Athens, Naxos, Bulgaria and the northern part of the Morea, you've effectively recreated Alexios' empire.
What would happen as a result of this? Would we see Slavization of the Roman Empire? A reconquest of Anatolia and Bulgaria?