IMO Marshall wouldn't be that hard to get along with- for anyone. You just have to account for the unique psychology of him, but also the unique mindset from many UCF players as well.
As a former Golden Knight, there was always this shadow cast over our school from FSU, UM, and UF. In this light, many UCF'ers can tend to be a bit rogue-ish, independent-minded, a bit exuberant in self-proclamations, and seemingly very proud. This can come off as "diva"-like but it really can be rooted to the high ambition to prove the greater, and truer, worth of oneself from out of the unwanted shadows cast over them. It's like a deeply embedded up-start/underdog mindset looking to find validation/recognition or to constantly build up one's prestige and social value. UCF is a thriving school, but it is still young in comparison to the others. Like it's city in which it resides, it hasn't plateaued- just continues to grow into something bigger.
It has nothing to do with selfishness, or team concept, but an untapped potential.
From that perspective, it's easier to read Marshall bravado, and also when he enters the up-start mindset that sometimes needs coddling or recognition. Just realize, that like in Denver, when used properly (new OC plz), he can be a power to be reckoned with.
Just sayin'...