Who is Ezra from Earth Abides and what is their importance?

Ezra meets Ish and Em soon after the two of them set up house together. Ezra has the ability to help others work well together, to smooth over tense situations and to make friends. Ish says that it's a testament of that ability that he has two wives and that the two often work together, never seeming to argue or become jealous. When Charlie arrives on the scene, Ezra backs up Ish's concern that the man is trouble and Ish, saying that Ezra seems to like everybody, is relieved to have the man on his side