here's my theory : Diane was heading to the hospital when she called Jack, who btw was out of the country . Chuck needed that transfusion fast, and Jack didn't make it in time, so Diane gave him her blood and covered it up , saying Jack did , and now Jack comes back to help Chuck find out what really happened ...any of this makes any sense to you ?

That's quite interesting idea. But why do you think her blood was good for Chuck? Do you assume they are related somehow?

Do you assume they are related somehow?

yes! Chuck somehow knew her , and in the beginning , she stole something , I can't remember what,from Bart's safe. I hope she's related to him :D it would make for a great storyline :D

It was a photo with an young girl, Laura. And it's possible,it'll be really interesting.

Do you think she's related to Chuck through Bart (some relative from his family, maybe sister) or his mother?

I don't know; I've been trying to figure this out. I had forgotten that Chuck had needed blood donated to him. There's got to be some tie with her and Chuck. With Jack coming back I'm sure we're going to figure it out.

Well it wasn't Jack.