Grey's Anatomy: 4x13 - Piece of My Heart

• Addison returns to perform surgery on a baby with its heart on the outside; Bailey catches her up with the latest goings-on at SGH
  
• Addison thinks Callie and Hahn are a couple; Callie freaks, does a bunch of shots, and goes home with McSteamy
• Meredith's clinical trial starts with the bear attack victim with the brain tumour; He has become extremely emotionally volatile; He dies in surgery
  
• Derek and Meredith bond somewhat over the case; Addison tells Meredith to not let McDreamy get away
• Ava returns; She tells Alex that she's pregnant with his baby; But, Ava really isn't preggers
• Cristina confronts Hahn about refusing to teach her; Hahn blows her off and then confesses that Cristina reminds her of herself
• Izzie invites herself to play darts with George and the interns; George reminds Izzie that he is an intern and she is a resident; Izzie gets it
• Izzie convinces an HIV+ not to have an abortion as there is a 98% chance that the baby won't be infected