I think it's about how women might try and change who you are and make you who they want you to be, until you've lost your complete train of thought and she's sucked the soul out of you, hence the parts where it says "You soul sucker" and "I won't become like you" and "I won't lose myself in you." Sure, she's seems innocent and beautiful at first but she's really just a "demon with a smile of gold." The whole part where it talks of her being back might mean she's been dumped by a previous lover but now she's found another man that she wants to change, or it may just be a way of introducing the band's new album and continuing their story or whatever.
But I could be wrong...