The more I read about Arazni and Iomedae’s relationship, the more I become fascinated with it and the more I really want the latter to survive.
Iomedae was originally a paladin specifically of Arazni (Inner Sea Gods, 77), back when Arazni was Aroden’s herald—and Iomedae was also the leader of the Knights of Ozem (who considered Arazni their “patron saint” (Knights of Lastwall, 8)) who bound her and forced her to lead the Shining Crusade against Tar-Baphon*, who ended up killing her, allowing her to eventually be transformed unwillingly into a lich by Geb (Knights of Lastwall, 9).
Arazni’s whole thing as a god (okay, not her whole thing, that’s a bit reductive), of course, is that she doesn’t forgive (see, for instance, her edicts in Gods and Magic, 54). And yet there’s no specification of her holding the hatred one might expect towards Iomedae (although she absolutely has a grudge and is resentful, she doesn’t seem to blame her)—in fact, “a small part of her takes comfort and even pride in Iomedae’s achievements” (Eulogy for Roslar’s Coffer, 72).
*I’m not sure if Iomedae was the one who bound Arazni, or if she even gave the order for it, but there’s no specification that she didn’t, and frankly, it would be weird for something this big to happen under the leader’s nose. The idea that Iomedae gave at least tacit approval to binding Arazni is supported by their creator, Erik Mona, in this thread although, as he himself notes, messageboard posts are generally only “quasi-canonical”.