More comfortable territory.
She is a paladin. At home, that would all by itself tell people almost everything they needed to know about her; paladins work hard to make sure that they are accurately understood everywhere they might need to operate. Much of the power of a paladin order is that the gods have vouched for the character of everyone in it, and the order for its members on a finer-grained level than that. People should be able to trust paladins, not just if they are themselves geniuses and clever negotiators but even if they aren't; people should expect to be dealt with justly. And people should frankly be afraid. Paladins are fearless and good at killing things. Iomedae is really, really good at killing things, and has not shaped herself in such a way as to hesitate to resort to it when her evaluation is that it's necessary.
She's from Golarion, a place that is so strange that none of the strangenesses of this world have struck her as something that couldn't be at home, a place with dozens of different kinds of magics that vary from one another more than Gifts do, and dozens of gods from Aroden, her ally and her friend, to Asmodeus, who she intends to kill someday when she's a grown up god herself. Avistan is ruled by Taldor, a declining empire that is in the background of her life mostly as a source of supplies and immense frustration, a place that feels broken on a very deep level she has no idea how to fix. She founded her own knightly order, partly to test whether everything is always broken like that or if it's possible to avoid, and it is possible to avoid. The Knights of Ozem are good. The thing that she has built to be her Church once she ascends is good. It's possible for things to be better, it's possible to give people guidance that guides them well and not badly. It's very hard, but she doesn't mind that.
Some people say that paladin orders make predictable mistakes in the direction of - releasing people who will do evil again, preferring inaction to blood on their own hands, being manipulable because of their desire to appear righteous. People do not in fact say this about the Knights of Ozem. There is an hourglass, in their main training hall, whose every grain of sand - thirty thousand of them - is a person dying. They turn it over ever day. It's their best estimate of the count across all of Golarion. A paladin of the Knights of Ozem repents of every one of those deaths, when they pray before sleep, not just the ones they personally caused. Iomedae has herself made estimates of the numbers across all creation. They're probably a thousand times higher. It's those that she reflects on before sleep.
You have to be careful, as a human, when you lift a heavy load, to lift it correctly, so you don't wretch your back and have lifelong back problems if you're too poor to afford magical healing. You have to be similarly careful, to take on the responsibility for everything in the universe going correctly without doing yourself an injury magical healing can't fix. You have to possess, already, the compassion of the loving gods, the conviction that you and everyone deserve peace and joy and growth and comfort; you have to love people, really and sincerely, to see their flaws without turning away from them in contempt and disgust. You have to love yourself, to see your own failures clearly enough you can grow out of them. You have to have your own measure, so you don't try things you can't achieve. You have to learn the strength to do things every day that will probably fail, and hurt, because if they were to succeed they would have been worth it. You have to be ready to kill people without ever forgetting that they should have lived, that in a world where you were better and stronger you wouldn't have needed to kill them. It's hard for Iomedae and harder, as far as she can tell, for everyone else. She's watched hundreds of zealous young knights make the same mistakes, try to fling themselves into a self-destructive self-limiting sacrificial desperation that is both the logical consequence of recognizing the stakes and a totally unhelpful attitude to have towards them. She knows now how to talk them through it but not how to protect them from ever getting there in the first place. The teachings of her church, once she has one, will be first and foremost a steady accounting of all the mistakes that brilliant ambitious determined people make when they decide that the world is intolerable and they're going to fix it, and they'll make the mistakes anyway, just maybe recover a little faster.
Ma'ar's mistakes are - not the usual ones, exactly, if she indeed interprets Ma'ar as the kind of person that she is, that her knights are, the kind of person whose stubborn conviction that they need to fix everything in the world crystallizes, on contact with reality, into 'I still need to do that but it's really really hard' instead of into some gentler things. His mistakes certainly remind her of some of the usual ones, but Iomedae is in fact not the kind of person who would conquer a country and provoke a world-risking war. Cooperation is the most powerful tool available to people who want to make things better; they share aims, in a way Evil never can and never will. To want to fix everything for everyone is to have common ground with everyone.
- mostly. She has spent the last several decades of her life leading the crusade against Tar-Baphon, an evil necromancer who looked likely to take over the world. They are fairly sure, by now, that they'll be able to push him back and imprison him at Gallowspire, but it's probably years and hundreds of thousands more casualties away, and they don't see good prospects of actually killing him in a way that'll stick. (He's a lich. You have to destroy the phylactery. He's probably done at least three of 'have many phylacteries' 'have a phylactery on a space-ship soaring off into the outer reaches of the universe', 'have a phylactery that is metaphysically indestructible' 'make something that Good really doesn't want to destroy, like the key to Rovagug's vault or whatever, your phylactery' and 'make a random unfindable rock at the bottom of the ocean your phylactery'.) He's smarter than Iomedae, by a large margin, smarter even than the smartest wizards on Taldor's side of the crusade. They're going to beat him out of their world, eventually, at an unfathomable cost, but she does not see prospects of actually ending him.
She does not have a lot of common ground with him. She would in the abstract prefer that he flourish, both the person he was when he lived and the twisted person he is now, but it is far outside her power to bring about in a way that protects others from him, the others matter more to her, and she would grieve very little, on ending him.
Once he's sealed she means to ascend. She doesn't have the details worked out, but - it does not in truth seem like the hardest thing she's ever done. New gods are weak and powerless, she can infer that that's part of the story, but she'll have a church already fervently praying for her. And Lawful Good's existing pantheon may be kind of frustrating but she doesn't think they're so useless they wouldn't intervene to help make sure she can get there and fix things up.