Arya Stark Timeline & Summary

Arya begins traveling north with Yoren and his Night's Watch recruits.
Goldcloaks come for someone, but Yoren scares them off. Arya thinks they are after her, but it turns out the goldcloaks wanted Bull, a.k.a. Gendry. Embarrassing.
After stopping at an abandoned village, Ser Amory Lorch finds the group and attacks them; during the attack, Arya saves the lives of the three men chained in the wagon.
Going back the next day, Arya discovers Yoren died in the attack.
Arya, Gendry, Hot Pie, and others begin the hard walk north, until eventually, they are captured by Gregor Clegane's men.
The prisoners are brought to Harrenhal, and Arya enters Lannister service as a scullion.
One of the men she saved from the wagon, Jaqen H'ghar, finds her and says he owes her three deaths to pay the debt for the three lives she saved.
Arya's first choice is Chiswyck.
Her second is Weese.
For her third and final death wish, Arya has Jaqen help her free Northern soldiers held prisoner in Harrenhal.
The freed soldiers and the Bloody Mummers take the castle from Ser Amory Lorch and present it to Roose Bolton.
Arya watches as Lorch is killed by way of bear baiting.
Realizing life is just as bad under Bolton's rule, Arya, Gendry, and Hot Pie sneak away from Harrenhal; Arya kills a sentry on her way out.