But before we see the presumed "you killed my father, prepare to die!" moment, things take a much different turn when Ashe gets involved with Vaan and co. and begins the journey to prove her birthright. Doubts begin to arise when Larsa proposes that Ashe seek peace with Archadia, rather than vengeance, and speaking with Al-Cid at Mt. Bur-Omisace reveals that war would be imminent between Rozzaria and Archadia should the resistance make a move. As Larsa explains to her before, Dalmasca would be the battlefield. At the same time, Rasler's ghost urges her to claim the shards of Nethicite and destroy the Empire. Other enemies, like Ghis and Gabranth, try to taunt Ashe into fighting them, saying she should enact her vengeance.
But Ashe's feelings change, and a lot of it has to do with the attitudes of her companions. Balthier warns her not to become a slave to the stones, using his mad father as an example of Nethicite's dangerous lure. Vaan proves to Ashe that many others have lost people just like she did, and, most importantly, there is nothing that can change the past. Reddas explains that taking revenge and using Nethicite is something more than vengeance: something beyond her understanding. He knows firsthand. In the end, the sentiments of her companions help in her decision to go against the Occuria and fight for her own right to be free, not for revenge or destruction. For her to want revenge is just what the Occuria wanted: for her to linger on her past losses (which Rasler's ghost helps fuel) and hate the Empire so that their own wishes can be fulfilled. But Ashe's ultimately proves that she's no one's puppet, realizing that no amount of revenge or hatred will bring those she lost back. She strikes down Vayne for her own reasons and averts the war.
Ashe demonstrates this attitude towards revenge again in Revenant Wings. Faced with a group of vengeful Aegyl in Ivalice poised to attack her kingdom, Ashe urges them to stop their attack, stating that, "revenge begets revenge. It is the fool's path." She continues to lament the foolishness of the Aegyl and their "god" through the course of the game, which certainly proves that her feelings on vengeance have changed greatly since her introduction in FFXII.
parallelRevenant Wings offers an interesting parallel to Ashe's story. A year after the events of FFXII, Ivalice is threatened by a mysterious "Judge of Wings," who aims to begin a war between Ivalice and the citizens of Lemurés, the Aegyl. As the story progresses, it's revealed that the Judge of Wings is merely a tool of the false Aegyl god Feolthanos, seeking revenge for his people having been cast out of Ivalice long ago. The Judge turns out to be a young Viera girl named Mydia: one of the Feol Viera (a race progenerated long before the events of the game by Feolthanos and his Viera wife), outcasts in their own right. Mydia's story made her an ideal puppet for Feolthanos: she harbored a great amount of anger in her heart for having to live hidden away in the harsh conditions of the Roda Volcano, accepted by neither the world outside, the Viera of the wood, or the Aegyl. She also suffered from a broken heart: like so many characters in the game, she lost a loved one during the war with Archadia. Her Hume lover, Velis, was killed at Nalbina. Mydia left on a journey to find answers and in doing so found Feolthanos, trapped by a barrier that gave him long life, who was then able to manipulate her feelings and make her a vessel for his revenge. Feolthanos even summoned an illusion of Velis to fool the young Viera into being controlled and thus could easily drain her anima (something like a life force) and turn her into an effective puppet. Mydia's tragic story ended with her slaughtering her fellow Feol Viera and subsequently fighting Vaan and his companions, who finally release her from Feolthanos' control, though it ultimately ends her life.
Mydia's sad story is very similar to Ashe's ordeal within FFXII and offers a look at what could have happened to the princess had she never overcome her lust for revenge. Would she have become a puppet of the Occuria and used Nethicite for destruction if she had never let those feelings go? Her anger, like Mydia's, made her an easy target for control. The illusion of Rasler, like the illusion of Velis, only served to further draw her towards siding with the Occuria. But unlike Mydia, Ashe was backed up by her friends and overcame her anger to make the right choice and follow her own path. I think Mydia's story offers a view into "what could have happened," had Ashe never had the support of her companions and taken the Occuria's bait. Would her fate have been just as tragic?