From what I've seen, most people seem to jump to the conclusion that the lyrics to "Dragonsong" are sung by Hydaelyn or Shiva. While both of these make sense to an extent, there are a few lines where this simply doesn't fit:

"A throne, lying empty. A reign, incomplete. Alone, for eternity. A pain, without cease"

To me, this seems like it is more likely to be sung from the perspective of Tiamat. She's one of Midgardsormr's first brood, but not as directly a part of the Dragonsong war as Nidhogg or Hraesvelgr. She fits well as a distant bystander that has done nothing but watch the war unfold in her grief for thousands of years. The part about being alone for eternity and feeling a pain without cease also fits well due to the fact that she has given herself that exact fate for what she did when she resurrected Bahamut. The only question that I would still have is what is meant by the throne lying empty and the incomplete reign.

Let me know what you guys think about this!