I'm starting the second book to the series I've been writing and my main female character has just come back from this world full of mythical creatures that she had been stuck in for awhile. She's on earth again now when these creatures from the other world suddenly start appearing on earth. They're evil creatures that want to invade earth and take over so her and her dragon boyfriend (that she fell in love with who has a human form) have to find a way to stop them without the humans on earth finding out. I'm stuck on thinking of a reason why they want to invade earth and I really don't know how I'm going to have them stop the creatures without humans knowing. I would really appreciate some ideas. I won't really take anyone's idea but I want to get my creativity flowing so detail would be great to so I can start imagining. Thanks!