Mormont girl
If GOT jumped the shark, it was when this girl showed up as the leader of that one clan. Talk about suspending disbelief. You might as well have had a golden retriever as the leader, would have been more believable.
shareTeenagers and even preadolescent children were often put on the throne in medieval times. In many places a regent, usually a relative, would make decisions in their name until they came of age. Not everywhere though. And it's pretty clear Lyanna Mormont is a child prodigy. Unlike that poor boy who was head of his own house and got crucified by the Night King, she has the mental faculties and the emotional maturity of an adult. Davos was the first to recognize this when he and Jon met her. And he immediately stopped talking to her like a child. Hey, it's a rare thing but it does happen.
shareYeah, children had to grow up FAST sometimes, back in the Middle Ages. Which was easier back when some people didn't have to bother with any real education, they could start doing an adult's job or marry as soon as they were physically capable and didn't have to worry about school work.
I wouldn't call Lyanna a "child prodigy", though. She learned the appropriate lordly bluster at a young age from her mother and grandmother, and is speaking for Bear Island before their liege lord, but I doubt she's actually ruling or fighting in battles. There's got to be some responsible adult back at her Hall collecting taxes and budgeting the servants' wages, and anyone who thinks the adults are going to let a little girl with no heir fight get anywhere near an enemy's broadsword, then that person is probably no older than Lyanna.