Origin of the theory that The Hound is one of the Three Heads of the Dragon?

[StarksInTheNorth]

So on the Prophecies page for the Three Heads, there's the following speculation/theorizing:

Using these points of data, strong contenders for a place as one of the heads of the dragon are . . . even the Hound.

I've poked around the internet but haven't been able to find any posts or metas about the topic. I was hoping someone could provide an explanation or link to someone who believes this for why this claim was made. I don't think my mind will be particularly changed by anything, but I am curious to see the origin and thoughts behind the claim.

Thanks!

 

I

[Tucu]

Maybe because he washed up in Quiet Isle like the dragon's head from the Inn at the Crossroad sign or Rhaegar's rubies (his blood)?

Quote

One of the dragon's heads washed up on the Quiet Isle many years later, though by that time it was red with rust

 

[Seams]

Maybe because of this?

• The Gravedigger
• Gravid three egg
• The dagger giver

This anagram could represent The Hound, Dany and Littlefinger. (Although Tyrion's uncle Gerion gave a dagger to Robert - Tywin later told Tyrion he could have it - and Joffrey said Tyrion could give him a dagger after destroying the book that Tyrion gave him.)

[Fool Stands On Giant’s Toe]

I want to see something with three severed heads.  

Three Lord paramounts combine into a Magor the Monsterous. Mwhaha!

maybe they mean something about his helm?

[Mister Smikes]

Sandor (he's not "the Hound" any more) will not be one of the 3 heads of the dragon.  He will, however, be a dragon slayer.  That's what true knights do, after all.

[Leonardo]

The origin? Stupidity