T.R. Knight and Katherine Heigl in Grey's Anatomy by Ron Tom/ABC T.R. Knight and Katherine Heigl in Grey's Anatomy by Ron Tom/ABC
Our series of Grey's

refreshers continues with a look at the highly controversial pairing of George and Izzie.

The Couple: George ( T.R. Knight) and Izzie ( Katherine Heigl) Where They Were: From the beginning of the show, George and Izzie have always been there for each other, especially when an STD (the syph) or LVAD wire-cutting was involved. The real test in their friendship came after George's dad died. George was so messed up that he flew to Vegas to marry Callie, again proving he isn't the sharpest scalpel in the OR. Despite the damage the marriage did to his friendship with Izzie, it only took one night of poor decisions to send George and Izzie spiraling toward a bad, bad (naughty bad) place. After some hot, drunken sex, Izzie and George realized that maybe what they've been looking for was right in front of them all along. The pair confessed their feelings for one another, and George ended his marriage with Callie. But there's just one problem: The couple's had some serious trouble recreating the hot sex they had that first time around. Whether they are both too tired or they're fumbling around in the bathtub (which they will "never speak of again"), George and Izzie have proven that they're both still interns when it comes to bedside manner. Where They're Headed: Izzie and George agreed that their timing was off and that they don't have the right chemistry as a "couple." It's going to be interesting to see if they can maintain the same level of intimacy in a friendship. Maybe they'll be best together as f--k buddies - after work they can hit Joe's and then stumble home together for more steamy romps, and then act like everything is normal the next day! Possible Roadblocks: Callie could pop up pregnant (pure speculation) or at the very least make George and Izzie's time on duty a living hell. And it wouldn't be Grey's if new love interests from the mind of Shonda didn't pop up to throw a possible glitch into future "Gizzie" hookups. Also, do we think Alex and Izzie are over for good? No way. Should Ava dump Alex for good, he'd be back on the Izzie train in a flash - but this time, for the right reasons. - Erin Fox Have more catching up to do? Use our Online Video Guide to watch full episodes of Grey's Anatomy now! And don't miss our photo gallery of Grey's Most Jaw-dropping Moments!