Heyo again Lore forum! I have more questions (since the Eorzean holiday one didn't work out so well...)

This one I think there might be an answer to, at least in some way or in theory.
So for awhile now I've been thinking of what Ser Alberic says about the 'Dragon Within' but it's never really explained much (Or if it is I can't remember). I know the Dragon Within along with the soul crystal (I think) is what gives the Dragoon their abilities that help them fight the Dravanian dragons... but that's all I know about it other then what's said in game.

Alberic mentions he almost gave in to the dragons during the attack on Ferndale and that's what lead to the loss of his powers, and then he mentions if your heart is full of justice the dragons can't control you. (That's kind of lopsided seeing as how justice isn't really something that can be define imo)

The only instance I ever seen of something like this happening is at the end of the boss fight with Estinein and his drake pet, where he calls out to Nidhogg to give him his power for one last attempt to strike down Alberic and then we transform into Haldrath and kick his ass out of there and he disappears... But that could have been because he had the Eye with him and not necessarily from the Dragon Within itself.

Anyway my question is:
Is the Dragon Within just another name for the Soul Crystal, or is it just something they tell fledgling Dragoons so they don't abuse the power they've been given when they fight the dragons?

OR is it actually something that resides in the Dragoons body, lying dormant until it comes into contact with a powerful dragon (like Nidhogg or, Twelve forbid, Bahamut?) and then the dragon, sensing it, tries to take control of the Dragoon? Kind of like a link to the dragons themselves. And what exactly happens when a Dragoon gives into it? Do they go into a rage, or do they just become a mindless puppet for the dragon?

If anyone can give me a clear answer or at least a very good theory, I'd love to hear it!