vaanAt first, Ashe and Vaan seem to have little in common. One is a princess, the other a pickpocket. One is royalty dead set on reclaiming her throne, and the other really wants to be a sky pirate. One runs around in sewers as part of a liberation movement, the other runs around in sewers to make some extra cash. On top of those things, Ashe doesn't tolerate Vaan's childish actions, inquisitiveness, and tendency to interrupt her. But as they end up traveling together, the two find that they have a lot more in common than they would have ever believed. Ashe comes to realize that Vaan lost everything he had after Archadia's takeover just like she did; he never had a throne or a royal title, but he also lost a family and a home. They also lost the people closest to them (in Vaan's case, his brother Reks) in the war, both of whom were fighting for their country's freedom.
Most importantly, Vaan reveals that he too has seen Rasler's apparition. It's not quite clear why he sees it, but when Ashe and Vaan talk in Jahara, Vaan says that he may be seeing his brother. Perhaps because both he and Ashe were lingering on their past losses, harboring hatred for the empire and wanting revenge rather than looking to a new future. Vaan also explainss to Ashe that he's done running away: done with seeking revenge and chasing hollow dreams just to escape that thought. Vaan says he'll stick with Ashe to find some answers, which she admits she doesn't have. But he says he'll follow her regardless.
When it comes to the point where Ashe must choose whether to wield Nethicite and side with the Occuria to defeat the Empire or go her own way, both she and Vaan announce that the past cannot be changed: that a thirst for vengeance will not bring those they have lost back. And so it's decided: they'll fight against Vayne and the Occuria by their own means. After the events of FFXII, the two reunite in Revenant Wings after the threat of the Yarhi comes to Ivalice. While Vaan still hasn't quite grasped the art of courtesy, both seem happy to be reunited as friends even under the dangerous circumstances.
basch fon ronsenburgUnderstandably, Ashe is furious when she first meets the newly-liberated Basch fon Ronsenburg, and greets him with a slap in the face. Basch, a former Captain in the Dalmascan Army who fought alongside Rasler, had been imprisoned for slaying the Dalmascan King. So Ashe isn't exactly happy to be fighting alongside the man who killed her father and conspired against her kingdom. However, Basch maintains that he was set up by his twin brother, Judge Magister Gabranth, who impersonated Basch to kill King Raminas and lay the blame on a Dalmascan traitor. Ashe is obviously hesitant to believe him. But Basch pledges his loyalty to Ashe and the resistance regardless and takes up Vossler's role as guardian after his betrayal. This unwavering loyalty eventually becomes apparent to Ashe as Basch becomes a trusted ally and diehard protector. Basch actually takes up his brother's former role of Judge Magister and guardian of Larsa after the game ends, but during the final FMV Penelo states that she thinks Ashe misses him. Ashe and Basch appear together again aboard the Leviathan in Revanant Wings, where he still seems just as protective of his former charge as he was in the original.
balthierPersonality wise, Ashe and Balthier are polar opposites. He's calm, smooth, and has no qualms about stealing treasure from tombs and royal treasuries, while Ashe is determined, cold, and rigidly committed to justice. Sky pirates are probably the last people Ashe wanted to become involved with, especially ones with bounty hunters on their tails. Ashe's righteous personality clashes outright with Balthier's generally nonchalant one during a number of occasions (i.e. treasure hunting in her ancestor's tomb), but he usually remains cool and collected even when faced with her serious and no-nonsense approach to their journey, much to her annoyance. But, like in the case of Vaan, Ashe and Balthier are revealed to have much more in common than anyone would think. Balthier also has a past that he needs to come to terms with, something that he seems to realize during the journey, just like Ashe does. Balthier also serves as a voice of reason against using Nethicite. Overall, he becomes a valued ally for Ashe and someone she really comes to care about, which is obvious when she begs him to escape the falling Bahamut after the final battle. She pleads, "you mustn't die! Please, Balthier. Come back." Of course, he makes it back safe and sound, and even remembers to return her wedding ring. (Ashe and Balthier also have a scene together in the sequel... which I can't make heads or tails of. Analysis pending.)
other alliesPenelo - Penelo, Vaan's trusted friend and fellow resident of Lowtown, is not nearly as straightforward and casual as Vaan, so she's probably a little more tolerable as a traveling companion from Ashe's point of view. It's safe to say that Penelo is a bit starstuck by Ashe and her status and remains apprehensive around her for most of the journey, which may be why they don't interact much. In Revenant Wings, Penelo is happy to see her old ally again, but worries that Ashe won't like her cooking and chastises Vaan for not addressing the Queen formally.
Fran - Fran, Balthier's Viera partner and voluntary exile from her village, is a woman of few words. She is, however, probably the oldest and wisest member of the party, and therefore the best source of advice and lore about Ivalice's history. Fran doesn't waste words, but when she does speak she's often being helpful. Fran is also fairly clear about her negative opinion of Nethicite (probably due to the Viera's harsh sensitivity to Mist), at one point stating simply that Ashe could destroy all of Ivalice with its power, which fuels Ashe's apprehension.
Vossler - Ashe and former Dalmascan Captain Vossler York Azelas spent two years together in hiding, orchestrating the resistance after he helped her escape during the invasion. But we never see them during that period, so we can only speculate on the nature of their relationship. Still, we can assume that the two were close and must have trusted each other after working together for that long. Ashe is clearly hurt when Vossler reveals his betrayal, even when he explains that he only wanted what was best for Dalmasca. Though Vossler really was trying for what he thought was best, but he made the mistake of a hasty and badly planned deal, alongside ruining Ashe's trust. But before he dies, he asks Basch to take up his charge, proving that he did care about Ashe, despite betraying her trust.
Larsa - Ashe is hesitant to trust Larsa Solidor at first, seeing as he's the younger brother of her number one enemy. She's appalled when Larsa comes to her with a peace proposal, but he does prove to be very sincere about wanting peace and helps Ashe's party out until the very end, even turning against his own brother. After Ashe becomes Queen and Larsa Emperor, Archadia and Dalmasca seem to be on very good terms.
Al-Cid - Al-Cid Margrace, a member of the ruling House of Rozarria, is downright flirtatious when he first meets Ashe ("Dalmasca's desert bloom"), even kissing her on the hand in front of her shocked/annoyed companions. At first, Ashe really doesn't want anything to do with Al-Cid outside of negotiations between their kingdoms, but But Al-Cid seems to be genuinely concerned about Ashe's wellbeing, offering her a safe haven in Rozarria. Like Larsa, he works for peace until the final stages of the game, no doubt making him a valuable ally.
Reddas - Reddas, pirate king and former Judge Magister, can strongly relate with Ashe's attachment to the past. He's also all too familiar with the danger of Nethicite, having destroyed Nabudis with the Midlight Shard years ago. Like Ashe's other allies, Reddas is a voice of reason against revenge and destruction. He ultimately sacrifices himself at Ridarona, for his own redemption but also to stop of power of the Stones after Ashe makes her decision. Ashe clearly appreciates his sacrifice, and goes on to prove that it wasn't in vain.