Denny & Izzie

I'm watching Grey's Anatomy as I'm typing this and am trying to figure out the Izzie/Denny situation. She's in the hospital "sex" room (seriously? they have a room where they do it) with Izzie going to town on him. Now, I don't mind Denny coming back at all. I think he's rather hot in a scruffy, big man kind of way, but I don't get where this is going and I have a feeling it's going to end up rather bad and it's bugging me.