That line of questioning really pulled me back to a specific scene in 'Devilish Smile'. It's less about a singular meaning and more about a motif that shifts with the protagonist's perspective. Initially, he sees it as pure malevolence, a taunt from something ancient and cruel. But after the well incident, when she smiles while weeping, the interpretation fractures. For him, it becomes a terrifying, beautiful paradox he can't solve. For her, it might be the only language she has left—a grimace of pain mistaken for pleasure, a shield of indifference over desolation.
Honestly, I think the novel leaves it intentionally ambiguous. Is it the demon's true nature leaking through? Is it a learned behavior, a mimicry of human mockery? Or is it a silent scream, a distortion of a feeling she can no longer express cleanly? The title ties everything to that image, making the reader as obsessed with deciphering it as the male lead is. By the end, I wasn't sure if I understood the smile at all, which somehow felt right.