Robin Arryn

For the bulk of his life, Robin was shamelessly spoiled by his mentally unstable, yet doting mother, which resulted in him possessing few of the traits expected of the heir to a powerful noble house. Instead, Robin is extremely temperamental, prone to hysterical fits and violent tempers. He also appears hugely entertained by the prospect of watching prisoners and enemies "fly" through the Moon Door, giggling and clapping excitedly when it was opened for Tyrion Lannister and then disappointed when Tyrion escaped execution.

Robin appears to lack a stable, if even existent, sense of empathy as a result of Lysa's doting. Aside from his unperturbed glee at seeing people thrown hundreds of feet to their deaths, Robin has also shown an insensitive and self-centered streak throughout his life. When he meets Sansa, he rather frankly details how he wanted to see Tyrion executed. He also shows confusion as to how one could live without the ability to throw people to their deaths, thinking that a home doesn't make sense without it. After he accidentally ruins Sansa's snow castle, he denies having ruined it at all on the basis that it was already 'ruined' for not having a Moon Door. He did not take into consideration that this was Sansa's family home, which she had been deprived of for years, and that she was trying to recreate her memory of what home felt like, and he'd ruined it. When Sansa confronted him, he lost his temper and continued destroying the castle. Even Littlefinger remarks that Lysa should have scolded Robin once or twice a long time ago, telling Lysa to consider Sansa hitting Robin to be a step in the right direction.

Robin seems to have a limited vocabulary – when younger, he refers to executions as "seeing people fly" but later refers to it as "throwing through the Moon Door" – and appears to be intellectually stunted. He also refers to Tyrion Lannister as "the baby man". He is often easily distracted, shows little sense of resolve, and struggles to come to conclusions that were obvious to everyone else.

Robin is also physically weak for a boy his age, likely because of the cushy upbringing his mother gave him. While training under Lord Royce at Runestone, Robin was shown to be hopeless with a sword. Even after prolonged training, he still can't even strike the widest ring on an archery target, struggling to hold a bow stably in his hands. However, while under Royce's care, Robin appears to have matured somewhat. He comes to the conclusion - though shaped by Littlefinger's manipulations - to send the knights of the Vale to support Sansa and Jon Snow's war effort against the Boltons on the basis that Sansa is his cousin, showing that he has at least some semblance of family honor though not particularly caring about the result of the war, flicking his hand dismissively after making his decision.

Though Robin is mostly silent throughout the proceedings of a Great Council in the Dragonpit, he appears to have matured a good bit under the continued tutelage of Lord Royce. Throughout the proceedings he holds a rather lax candor, sitting back in his seat with his leg crossed over the other. He laughs at the idea of a democracy, clearly understanding what it would mean for him and his power, and is embarrassed when his uncle, Edmure, attempts to become king. It is unknown if Royce ever told Robin the truth about his mother poisoning his father at Littlefinger's behest and then Littlefinger killing his mother as well.