@caseyrybek: The way that I interpreted the part with the Night King choosing a dragon is that Vyserion had his vital points open, whereas Drogon was stationary while facing away from the NK and his wings covering his body. The night king got Vyserion right in the jugular.
Their whole plan with convincing Cercei to truce, she doesn't really have a choice. Danny/Tyrion and friends know that. It's either join us to fight zombies or kings landing burns. To get to the Night King they would have to get past his army. Nk's army still outnumbers the north + the unsullied, they need the south too to break NK's army.
What is the indication that white walker have a difficult time in the water? Nevermind that. The NK has control of his army. He can make them go in the water and pull the dragon out. The chains are a very minute detail. I don't know why people are hung up on it. The NK has been around for thousands of years you'd think he'd come across some chains.
Man these nitpicks are so obnoxious. A lot of these are already explained in the very episode. The only valid point is that the pacing is out of wack, although that's to be expected without only like 7 episodes left in the entire series. They need to do a better job at indicating time skips.
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