Alex Karev is unmoved by Izzie's confessions of having sex with Denny.

In a photo from "Brave New World," from Season 5, Meredith, Izzie, Cristina and Alex look on during a typical day at the hospital.

It may be a "Brave New World" in Season Five of Grey's Anatomy for Meredith, Cristina and Izzie, but there's still time for some lighter moments. In this case, sitting on a couch!

A photo from the fourth season finale of Grey's Anatomy, "Freedom." Izzie Stevens has reached yet another professional and personal crossroads.

Dr. Izzie Stevens (Katherine Heigl) is all smiles in this promotional photo for "These Ties That Bind," from the turbulent but terrific fifth season of Grey's Anatomy.

Izzie's mom makes her first appearance on Grey's Anatomy. Somehow we imagine this is not going to go swimmingly for our girl.

Izzie's mom makes an appearance in "No Good at Saying Sorry," the April 30 episode of Grey's Anatomy, and Izzie is not looking altogether thrilled in this picture at least.

Cristina is always out to get ahead, and here she is up to her old tricks yet again in this photo from "There's No 'I' in Team," from Season Five of Grey's Anatomy.

In a still shot from "Losing My Mind," from the fourth season of Grey's Anatomy, Mark and Izzie have a serious conversation at Seattle Grace.

Dr. Izzie Stevens treats a hurting patient, who is wearning a look of concern (and searing pain) in this still shot from "Where The Wild Things Are," in Season Four of Grey's Anatomy.

Izzie Stevens attends to a car crash victim (or so it would appear) in the Season 5 premiere of Grey's Anatomy, "Dream a Little Dream of Me."

Grey's Anatomy doctor Isobel Stevens, better known as Izzie Stevens and played by Katherine Heigl, has yet another run-in with her late fiance, Denny.