The Alien

[DarkPrimus]

Who/what was the alien?
What was it doing?
Why was it doing whatever it was doing?

I've got my own theory that I'll post tomorrow, but I'm curious as to what the rest of you people think.

[Cetacious]

Well, I don't take the alien as a character which does things by motivation, it's rather a thing set there to show us some stuff. The first time it appears, it's to start breaking this barrear between wired and physical world, between reallity and fiction. That's basically what that entire eppisode is about, hence the mixup between anime and pseudo-documentals which give us the feeling that what we are watching may be part as much of our world as it is of Lain's. Now aliens in general stand more or less in that position, cause many people believe them tp be real and many people say they're not, so they're halfaway between reallity and fiction, like Lain.
But when Lain appears in Arizu's room with alien body, I think due to the context that refers more to her identity thing, since she has discovered it's not her body which determines her, se symbollically changes it, just to show she can. Besides, as far as I remember, she was also kind'a scared at the moment of herself not beeing human. Aliens are also scary out of that same reason.

[iwakura]

There are many interpretations for the alien Lain.

I take a more literal one to tie into the Roswell New Mexico stuff. The wired was based on alien technology. So, having an alien Lain just makes sense.

Also, there is the potential for the wired to not just include earth, but other worlds...

So, the alien was just another aspect to Lain in addtion to the usual "Yin" and "Yang" Lains.