I wasn't really paying that much attention to it at first, but when the Blades shouted "Hail Dragonborn!" I was intrigued.
That would mean one of two things: Martin had fun before we met him, or Uriel and Jauffre trolled us the entire time and didn't tell us that there was a second illegitimate heir to the throne.
Now what I want to figure out is this: ALL 10 races can be the Dovahkiin in Skyrim, so what exactly would your linage be for your character?
I'm thinking as hard as possible, but I can't figure out what happened from Martin (or unknown heir #2) all the way to my character. I invite you all to succeed where I have failed.
(I don't know if the Dragonborn existed out of the Septim bloodline, but I'm assuming you're from that since you have at least one member of the Blades helping you through the game).