lots of discussion earlier about character ages in comparison to the books.
The question for me is, how much of the TV show is literally based on the books in that regards? Daenyres might only be 13 when she has sex with Drogo in the book; the actress cast is much older, but that would not resolve the issue with the character having sex on TV at such a young age, so maybe the show actually increased the ages in the story itself, for its own purposes? Likewise, maybe casting older actors for some of the roles (like Robb?) means he's not 16 in the TV show, even if he was in the book? It's unclear. But this type of translation happens all the time. Robb seems written as far older than 16 in his intellectual capabilities in the show.
I see the whole debacle at the Twins stemming mainly from Rob making a few errors that did not seem fatal at the time but in the world he actually lives in positioned him to be very vulnerable, and his enemies exploited that. One of them is commented on in the show ("You lost the war as soon as you married [Talisa].") That marriage was a huge bartering chip to seal an alliance, and Robb threw it away. Another was his broken vow to Lord Frey, who already was kind of unpredictable, stubborn, and provided him with a service that he was reluctant to offer at first; and Robb took it SO lightly, even when he formally offered an apology. Another was the execution of the Lord who murdered two Lannister hostages, in such a complicated situation, against the wishes of every one of his advisors on the matter and a prediction of what would happen -- leaving him vulnerable to needing more men, thus needing to deal with Lord Frey. And a final mistake was simply trusting that the old rituals would matter in a time when the entire land was in upheaval and his enemies so desperate.
Small mistakes, and another enemy might have not taken advantage of them or played more conservatively... but he was dealing with Tywin Lannister.
I agree with that. I really don't like Tywin as a person, but as a character he seems to be everything he's cracked up to be. Dance conveys him wonderfully.