please update it

I think you should have Lucifer knock Emma out, not kill her. If you kill Emma the story may lose some of it's touch. Have Lucifer go out and look for Kayla while Emma is still knocked out at the house, where she later wakes up and meets whoever switched them...just don't reveal exactly who it is, maybe give us a description of what he/she looks like.

On Kayla's side of the story, I think you should have Mark take her to the set of Supernatural where she is confused and stands on the sidelines as she watches Mark talk to the producers. She fells a tap on her shoulder and turns around to see Lucifer...Bam! End of chapter! :D

That's my idea's, you can take them or leave them, I don't mind :)

Oh boy this is good, this is so going in my favourites! :)

Great story. Love the idea. And you're writing style. Usually I find a good plot but bad writing ( no offense to anyone, you're all great) or bad plot and good writing but you have the best of both worlds!

I can't wait for the next chapter :D
and I like #4 and Emma should tell Mark :3