In this passage from "Eclipse" by Stephenie Meyer, the character Jacob displays a significant change in his expression, shifting from a smirk to a wide grin. This transformation suggests he is entertaining thoughts of Charlie, likely a figure of authority, coming to arrest him, which adds a layer of irony to the moment. The grin, however, carries a bitter and mocking undertone that feels unsettling.

The narrator reflects on the fact that Jacob's reaction doesn't evoke the joy or satisfaction they had hoped for. Instead, it highlights a complexity in his emotions, suggesting that this isn't the genuine or reassuring smile they had anticipated. The conflicting feelings create a sense of disappointment and tension in their interaction.