Private Practice-Grey's Anatomy Spoilers: McDreamy's Past

When Grey's Anatomy and Private Practice become intertwined a week from tomorrow, Addison and her brother Archer will be dishing some serious dirt on Derek - as in stuff from his past that Meredith has not been aware of until now. Sam and Naomi, who went to med school with the former spouses, may also be getting in on the action?

What will they reveal about our beloved doc - and how will Meredith react?

Find out more about these Private Practice and Grey's Anatomy spoilers!