Maybe I'll do the zen meme that's been going around, but in general I am pretty zen, so instead, headcanon.
Ash knows a very little bit of conversational Yelorrean. However, he knows how to swear in it and several other languages.
He likes People more than he likes people. The idea of humanity, of improving life for people as a whole, seems more appealing to him than individuals. While he works on small scale, (writing pamphlets, spreading rumors, attempting to distribute information) he's a wide scope thinker.
He can envision a future in which he and Kieran grow old together, or a future in which they somehow manage to lead a successful uprising against the White Watch and free the nations that make up the Commonwealth. He cannot imagine both of these things simultaneously.
He chronically underrates and undervalues his own power, simply because Kieran has so much more of it.
If Kieran died and didn't come back, regardless of what he'd promised, Ash would kill himself. He does not expect the same from Kieran.
Ash views camp as a fundamentally temporary place, and the people he befriends there as equally temporary. Regardless of how close his relationships appear, if he and Kieran had the chance to leave, Ash would never look back. This also means he doesn't really care what people in camp think of him unless a) Kieran likes them or b) Ash perceives them as dangerous. It's no skin off his back if anyone thinks he's an idiot or a weirdo.
He hates camp, more for the fact that he can't hate it completely. An interesting, relatively comfortable prison is still a prison, but it's also still relatively comfortable and interesting.
He still bites his fingernails, but less now that he has things to fiddle with.
He misses his longer hair only because Kieran likes it.
He is completely oblivious of any charisma he has. He's also incapable of thinking of himself as being even potentially attractive. The boy knows for a fact that his boyfriend finds him hot, and can see no logical reason why.
Ash doesn't like killing people, but he won't hesitate to. If talking fails, he absolutely will shoot.
In his opinion, the moogles cheapen death and killing. He finds the revolving door distasteful, even when applied to his friends. In truth, it would probably freak him out a lot less if it wasn't based on moogles and save points. Putting a soul back into a body is different than rezzing at the last save point.
He's always, always carrying a tiny steno pad and some sort of thing to write with.
He never takes off his ring. Ever. And even still, he put a little locating spell on it, so he can find it if it gets lost.
Doing the housework honestly doesn't bother him, as often as he grouses about it. When they go home, he believes that it will be all Kieran caring for him again because he can't take care of himself, and doing the cooking, cleaning, and laundry is the best way he can think of to return that favor.