Honestly, I think a lot of those stories thrive on the tension between his inherent chaos and a character who represents some kind of order. He’s a force of nature, right? So you drop in an OC who maybe has a moral code, or a duty to the realm, or just a desperate need for stability. The conflict isn’t just ‘he’s bad, she’s good.’ It’s that he finds her rigidity fascinating, even irritatingly attractive, while she’s both terrified and weirdly liberated by his willingness to burn it all down. A common thread I see is the OC trying to ‘tame’ or understand him, only to realize she’s being changed more than she’s changing him. That internal war—wanting the safety she’s always known versus craving the dangerous freedom he offers—feels very true to the world of 'House of the Dragon.'
Another layer is legacy. Daemon is obsessed with Targaryen supremacy, bloodlines, all that. An OC from a lesser house, or even a commoner, introduces a class and blood purity conflict that’s baked into the lore. Can he truly value someone outside that Valyrian bubble? Or is the relationship just another transaction or rebellion for him? The best fics I’ve read make you question his motives right along with the OC.