"Could it be Izzie dreamed Denny died? Now this is all part of her dream. Maybe she was in a car accident or something on the way back to the hospital and has been in a coma? She is starting to wake up and Denny is there with her talking to her. It would be a little weird, but it could explain things. It would also be a way to bring Denny back that makes sense."
"Now, this is a really dumb theory, but i heard that this is ALL a dream. I read (I cant remember where) that in the last episode of season 5, Izzie is going to wake up in Denny's hospital room, and he is still alive, meaning that everything in the past seasons (except seasons 1 &2) was a dream."
You are missing a crucial part, the show is called Grey's Anatomy, not Stevens' Anatomy. Izzie can have a great storyline but not a protagonic one, because it's Meredith's story. If Izzie wakes up and it's all been a dream, it means that we saw three seasons of Izzie dreaming which is not gonna happen because this is not Samantha Who or Eli Stone haha, I think Izzie will have some sort of disease.
