RandV
It's a wolf v2.0
Like I have said before, specifics with regards to a character are important. "Propensity to be violent" is a very vague term that can apply to people among various moral standings. Gregor Clegane had a propensity to be violent. Are we saying that Gregor Clegane and Daenerys Targaryen are morally equivalent or are equally prone to murdering civilians? Sandor Clegane had a propensity to be violent, and there is a clear line between him and Gregor because of what they specifically do during the course of the series.
Specifics do matter, especially when it comes to transitioning from a moral or generally moral perspective to a grossly immoral one.
I wonder how much of this was just a divergence in writing between GRRM and D&D. What I mean is up to the end of A Dance with Dragons, Jon and Dany's stories paralleled each other: rise to position of power/authority at young age, initially show a lot of promise, start to buckle under pressure as the world beats down on them, then everything goes to shit. You could say there's meaning in the narrative here, that you have to fall before you can run, but while my memory is set on the book and I'm having a hard time remembering the specific details of the show I feel like Dany never really 'fell' here, her situation was a lot kinder and it's more like they chose to Mary Sue her.
Yes she's almost assassinated and ends up flying off on Drogon, that's the same, and the book ends with her running into some Dothraki so the events will probably go somewhat similar there. The problem is I feel like they kind of Mary Sue her from there, she charges into Mereen and saves the day, leaves Dario in charge and sails to Westeros with a massive unbeatable army. The main difference here is in the books Mereen is a complete shit show where you feel like if/when Dany rides in with the Dothraki she may as well burn it all to the ground. Putting some details together with early preview chapters (I believe) released from Winds:
[spoil]
The other two dragons are loose and the city huddles in fear as they roost in pyramids and terrorize with impunity, the besieging army is succumbing to the bloody flux/plague and catapulting disease ridden corpses into the city to spread the love, and finally a Greyjoy armada is barrelling down on the city lead by an unrelenting Victarion Greyjoy who is much less friendly than Yara/Theon and has a magic horn from old Valyria that will supposedly take control of dragons.
[/spoil]
Overall along with the other painful lessons learned (like the Butcher king) just feels like a much more volatile situation that would start the transition to "Fire and Blood" Dany that just wasn't there in the show.