Phee makes a really good point. I don’t think plot device is the correct term for Lacey. The BF is a plot device because her appearances are simply used to advance plot without any logic to it (specifically a Dues Ex Machina). Lacey did serve a purpose to the overall plot of Rumple, Regina and even Belle. Maybe it wasn’t the best story or the most well thought out story, but Lacey did serve a purpose.