I've been thinking, which is almost never a good thing, about where the Haibane came from or why they show up the way they do. I came up with a little bit of a theory, so don't take offense or freak out. This is kind of long and I don't really know if I'm explaining it correctly but hey it's worth a try. Let me know what you think, after all it's always fun to discuss ABe more in depth. Don’t insult me if I didn’t read up on this idea beforehand, it just came to mind. So Here Goes:

The Haibane are named based of the dream they have in the cocoon, but what does that dream really mean? Rakka believed that the crow from her own dream was someone she hurt badly and need forgiveness from in order to no longer be sinbound, if I am not mistaken.

So maybe these dreams that the Haibane have are in fact the last final moments of their lives before being Haibane, and perhaps how(or if) they died.

We take Reki for example, Reki's true name was To be Run Over (something to that extent) and her dream was scary. Her dream was a vivid portrayal of exactly what happened when she died, which is what made it so terrifying. Reki, as we all know, was run over by a train whilst walking on it's tracks.

Other dreams, like Rakka's or Hikari's are recalled pleasantly, perhaps because the reality of death was too much to handle.

Hikari remembers a brilliant light from her dream. Perhaps she was struck by lightning? Or maybe electrocuted in some manner or another? Or maybe she died in a fire? If you really want to go on the dark side, you could say the Haibane had committed suicide in their past lives, but this doesn’t explain the presence of the young feathers. Most children as young as that don’t even know what suicide is much less how to commit it.

Kuu remembers falling through clouds, and Rakka recalls falling as well. Perhaps they both suffered falls from high rise buildings, a plane crash, or even a short fall that resulted in their death.

Nemu was sleeping. Perhaps that’s how she died, suddenly and in her sleep.

Kana would mean being drowned.

The crow in Rakka’s dream could easily represent a relative or friend who was with her when she passed and tried to save her, but couldn’t. Rakka seeks forgiveness for hurting this person who tried so desperately to save her from an inevitable fate.

Whatever the case may be, my theory is that the Haibane are former human beings who suffered a quick and shocking death, and subsequently are unable to cope with that fact or are completely unaware of it.

So you and conclude that the Haibane are the souls of the dead who haven’t come to terms with losing their lives. When their day of flight arrives, that is the chosen day that they are sent to heaven, nirvana, whatever you may wish to call it.

I could keep going with this, but then that would make this excruciatingly long. So what do you think?