i honestly think lee sunkyung took over shin sera's body so that she can live her "flawless" life and that the real shin sera's soul got sent to another body - either our mc's or lee sunkyung's og body (since it'd be empty as the soul went into shin sera's body). it'd explain why shin sera was so violent like lee sunkyung. since the real shin sera (our mc) is back inside her body, as is lee sunkyung which is why shes tryna sc*** mc over