I thought that this weeks #GameofThrones was pretty great.pic.twitter.com/kzDCDC4xHS
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Also, I don't know if you've read up on the lore of the world and such, but Targaryens are naturally capricious and volatile; the wickedness is baked into their DNA from birth. Dany didn't need some elaborate character development to reach that point.
She's literally been hot-tempered the whole show, burning people alive for slight disagreements and making bizarre choices. So naturally, when her closest tethers to normalcy were servered, she snapped, as has been palpably foreshadowed the entire freaking show.