A couple of characters that come to mind:
-The fallen paladin, in D&D i once roleplayed a paladin that, after some adventures, "fell from the grace of his god" because he refused to kill a demons in cold blood (i think i was a paladin of Tyr, or some other extremely & zealot lawful good deity). That character was loads of fun to play as (even tho he sucked (stat wise) after he lost his powers), as you usually only see "dying" or "evil" fallen paladins in videogames or other medium, making one that can actually live up with the "fallen" status might be a interesting ideia. With all the romance present in the game, maybe the paladin could have found love with a demoness and thus was cast out?
-On the other side of the coin, a honourable demon. Not sure if your aware of Planescape's lore, but there is a city ( or more correctly, a plane of existence) where both "Lawful" angels & devils live together, they belive that as long as you stand for Order, not matter if for good or evil, your a worthy person, as the worst thing that can happen to the world is senseless chaos. With what Myrth said, maybe we can have a Demon that thinks akin to the above ideias?
-Another "creation" of mine, a Medusa that is seeking her lost sister, which was captured by mages who want to do experiments concerning turning objects and people into stone. In my game (as DM in D&D), the party of players relunctly helped her, but only to find her sister beheaded, to which i did write a rather sad scene where the Medusa burst in tears.
-A orc character (or any traditionally "monster") character turned into a proper character (not sure if its possible in Aravorn) to challange what the players think who are "truly monsters".
-As a DM in D&D, i always LOVE to challange my players preconseption of pretty much every adventure cliche.
You find humans & orcs fighting along the road, in the middle of tradecarts, what do you do? (usually the players attack and kill the orcs), but if i am a DM, they find out the humans are the actual bandits
Some other random ideias that might inspire you:
--Goblins being used as slaves by elfs
--a Beholder saving the party's lives because he figures being binded to one place actually sucks.
--a Lich that doesnt want to conquer the world, only be left alone.
--Paladins being actually "EVIL", as you know, the line between Lawful Good & Lawful Evil can get pretty THIN when one is a zealot.
I would say a Viconia type character from Baldur's Gate, but i feel we already have the "bad girl with a good heart" in the game, so no need for that
Hope that i might help you. I have been DMing for more than a decade now and as you can imagine, making up fantasy characters for an adventure (be it for a P&P RPG or videogame) comes rather naturally for me (of course, none with as much depth as yours), but i like to think they might be interesting concepts, maybe they also spark some ideias for you!