THIS IS EXACTLY THE FEELING I HAVE, that a future storyline will involve coming to sympathise with a darkspawn, and learning they are not so different after all!
I see what you mean. If the song is a kind of life-force, one end of the spectrum could be life as we know it - the other end, darkspawn... what you say about the Architect's tactics seem to be moving along that spectrum. Unless he was just experimenting on Wardens, as special cases? Or did he experiment on normal people too?
I have this terrible feeling that darkspawn will have "diverted" fade souls put into them when broodmothers conceive... from what we are told about darkspawn fighting each other almost immediately after being born: "they will try to kill each other, perhaps a natural instinct"... do they retain memories of being something "better" before? DO NOT WANT.
Ok that is wild speculation! But I cannot decide what I think the taint is D:
1> I am open to the idea of the collected diseases known as "the taint" having been a biological weapon gone wrong, manufactured by our Ghil.
2> Also open to it being more spiritual in nature, aka "Pestilence", one of the Four Horseman/Forgotten Ones
3> Also to Tevinter magisters being tricked by their gods (if not the Forgotten Ones) into bringing back the taint with them from the Fade
I cannot decide *sobs* ;-; want to know so bad!
WoT on Archdemon song:
The call of an Archdemon can be heard by darkspawn over great distances. Wardens may hear it too, one clear signal that a Blight is looming. What the call is exactly has proven hard to define. In a Warden's ears, it sounds like strange music, an intoxicating melody that grows louder and more appealing as the corruption advances. Darkspawn are consumed by its draw and can think of nothing else but uncovering its source.
So reasoning:
1> there is a correlation between an increase of "corruption" and an increase of "Song".
2> the darkspawn crave finding the "source" of the Song.
3> the darkspawn cease searching after discovering a sleeping Archdemon, presumably having found the "source".
Conclusion: Archdemons are both the source of the "corruption" [taint] and source of the Song.
I should stop putting off reading
The Calling, shouldn't I?

I bought it recently, which made my fiancé sulk since he had apparently bought it as a suprise present for Valentines! whoops!
<snip>
And in the last flight
All life is connected, confirmed?
If they're already tainted, then that's their source of nourishment.
If they aren't tainted yet, then it's probably something like uthenera. But then why call out to darkspawn?
Wait. What if it's not the archdemon that's calling out to darkspawn, but whatever spell has them imprisoned? To give it an image, you have this archdemon just slumbering away, and then this cage wrapped around it, and it's that cage that's calling out to the darkspawn.
Only, that doesn't really work because if it's just the cage, then the song should stop once the archdemon's set free, which it doesn't.
Yeeeessss my thoughts incorporate all these. Am currently studying different theories on "consciousness" at the moment so I want to see if I can incorporate them into theories about the song!