I don't think we've seen anything like you describe, OP. Demons seem to specifically form in order to ultimately dominate over the thing/person they're possessing - if only through twisting the person/soul themselves to become something that they can continuously feed off of and use as a puppet.
But I don't think what you describe could be always impossible. We very well could see a future story with some character either having remarkably strong will and character (and/or a demon with remarkably weak power) that we see something else happen. Or even a whole class/order of people who know this sekret skill, haha.
But so far, nothin. Keeper Marethari is a close example given above, but she also kept the demon restrained - she didn't go into a constant battle and domination over the demon itself to use its power.
So far, we have the basis that mortals, even mages, are no actual match for demons intent on taking them over. They are ticking time bombs and they do not have innate access to demonic powers. Spirits within a mortal may grant powers through co-operation, but demons are demons purely (barring some cool story in the future showing otherwise ) BECAUSE they want to possess mortals, use them as spiritual/emotional batteries, and know they're capable of doing so. They know they are/can be stronger, and that identity, well, makes them stronger than fallable humans.
Maybe we can see a human that has the strength to resist and it could involve cool magics and/or an anomaly (like the Shepard degree of willpower haha), but it certainly won't be a common thing.