In the case of Arya Stark, a girl has some seriously messed up adventures. When we first meet Arya, she's a young girl desperate to prove herself as tough and strong, but with no idea of how the world truly works. She's very similar to her older sister in that way, but that's where their similarities (and civility) ends. She never takes to the South as Sansa does, and instead works to learn as much as she can from Syrio Forel, her sword fighting teacher. When the Lannisters declare her father a traitor, she runs away, saving herself from being a prisoner like her sister.
While Arya doesn't go through the same hardships as her sister, she finds herself in numerous dangers situations. She makes friends with Hot Pie and Grendy Waters, before the Red Witch takes the latter away. She journeys with the Hound, though that doesn't last long either. Finally, Arya travels across the world to Braavos to learn how to become a killer and take revenge on the people who destroyed her family.
By the time she reunites with her older sister and brother, she's crossed off a few people from her kill list. When we last see her in season seven, she manages to make one more kill that isn't even on her list!