I just had a thought that I find interesting enough to mention. I'm not sure if this subject was ever addressed yet.

What reason do you think the zombies are fighting for? They are not mindless, so they must be fighting for a cause.

They have carried off their dead early on which leads me to believe they are somewhat sympathetic. The title, We're Alive: A Story of Survival, may suggest that both sides are trying to survive. It was said that Ink may have not been the one who started this... What if he's trying to fix it? What if all the zombies are sick and are looking for a cure, which could be the immunity that some of the survivors have. I must also say that the birth of the baby will probably be at the end of the story. That has to be some sort of climax... Thoughts?