Midgarsormr

[Yvresse]

Without getting into post-A Realm Reborn spoiler territory...

Midgardsormr's name is a reference to the World Serpent from Norse mythology—a snake so massive that it is coiled around the world itself. He has no relation to Final Fantasy 7's Midgar or Midgar Zolom, save for those names coming from Norse mythology as well.

He's the progenitor (read: super dad) of all dragons on Hydaelyn. You fought him because he attacked you. There are Magitek Robots there because the XIVth Legion (Gaius van Windbag's men) controlled the island you fought him on.

He sealed the Blessing of Light, preventing you from using it. You still have it, it's just dormant.

He might be stronger than Hydaelyn. He is probably not a primal.

And as for why he hates Ishgard, you'll find out in Heavensward.

So where does he come from if hes not a primal?