"Never tired, never frightened, never deafeated. He's supposed to be BUFF!"
...And if he doesn't feel like that at times, then he's a flat character. Believable characters DO need to rest and take a breather, they react to something frightening like how they should (depending on their personality they run away, they grab their gear and fight back, or they try to outwit the creature), and while they are supposed to be strong... one man can only take so much before he snaps and breaks from pressure and stress.
Even Lork!Cedric has more believability than the original!Graham if THAT is Roberta's stance on him. At least Lork!Cedric I'm TRYING to give a little character development to him, and trying to make him a better character.