Writers are often told their characters need to be “likeable,” but I think the better term is identifiable. Not that we want to be them — Olive Kitteredge, anyone? — but that we trust such people can exist.
Or as novelist Claire Messud Publisher’s Weekly, “If you’re reading to find friends, you’re in deep trouble. We read to find life, in all its possibilities. The relevant question isn’t ‘is this a potential friend for me?’ but ‘is this character alive?’”