Desire. It consumes us all, for better or worse. Especially when we want what we can't have... or don't even know what we want at all.

When the Chairman of the Board of Seattle Grace is admitted, Richard wants Miranda on the case because the attendings (all vying to be Chief) will be too consumed by their own ambitions. But when this VIP patient's shockingly enlarged genitalia is presented to the staff, it's all hands on deck.

It turns out that during a recent trip to the Amazon, a rare parasitic fish lodged itself in his urethra. Lovely. Moreover, unless Richard - who the disgruntled Chairman calls out for becoming too political and soft since taking over as Chief - operates, it could be fatal.

But his bizarre physical problem isn't the only complication the Chairman is going through. Worried that she may too be afflicted with whatever is causing him pain, his assistant, Celeste, confesses to George that she's been having an affair with him for five years. Her tests are negative, but clearly the event has altered her thinking about their relationship.

Preston, Richard and a whole team of surgeons operate and eventually get the parasite, which had grown large inside the man. But when he wakes up, he loses a lot more than that. Wracked with guilt, Celeste announced she won't be staying on as his assistant, and his wife, who just confessed to George that she knew about the affair all along, leaves as well.

With Miranda assigned to the Chairman, Sidney is in charge of the clinic, and has Izzie treat a man although it appears he has nothing more than a common cold. Lucky for him, Sidney was her usual thorough self, because they discover that he's leaking spinal fluid out of his nose. His brain is actually collapsing on his spine.

Richard tells a relentlessly hard-working Miranda she can't do it all if she wants to have a life and be Chief Resident. Meanwhile, the interns all cram for their big test as the end of their first year approaches. They're all struggling to deal with their complicated personal lives on the side, too, making it an interesting few days at Seattle Grace.

Cristina can't be bothered to sample wedding cakes for the hyper-involved Burke, wishing instead to obtain Callie's amazing flash cards to help her studying. Izzie and George, meanwhile, are completely inseparable - to a point where it's obvious to everyone, and maybe even a little nauseating (especially if you're trying to study)!

They love each other, even if they won't admit it. Callie doesn't think an affair took place, but she still begs Izzie to give her back her husband. A crying Izzie confesses - to Burke, of all people - that she slept with her married best friend. George tells Izzie that he's applied for a transfer to Mercy West. Not because he wants to. He has to.

Ticked at herself for telling Derek to stop hovering, Meredith shifts gears and tries to be super communicative and friendly. All day long. It's a bit of a reversal for the usually coy and sometimes distant Mer, but she keeps at it, updating Derek as to her whereabouts and feelings at all times.

But it's not clear if Derek wants her to be. At the end, after she shows up at his trailer unannounced, strips down in his bed and they have sex, he says he isn't sure he wants to breathe for her anymore. After this harsh remark (and reference to her near-drowning), a distraught Meredith leaves for home, with Derek alone in his bed.

Jane Doe/Ava is in much better spirits than the last time we saw her, and doesn't hesitate to update Alex on all the latest Seattle Grace gossip. A good listener, she's picked up on everything regarding Addison's 60-day no-sex bet with Mark, as well as the fact that Dr. Montgomery has been pining for younger Dr. Karev. She encourages Alex to go for it!

He's got more important things on his mind, though, when Ava has a seizure and her baby has to be delivered prematurely. As Ava panics during surgery, Alex comforts her, showing a side of himself that endears him even more to his boss, Addison. She finds him later and attacks him in the on-call room, stealing him away in the heat of passion.

Seeing this, a dejected Mark makes a pass at Meredith, but she immediately rebuffs his offer of revenge sex and tells him to let Addison go. When he runs into Addison later, Mark lies and says he slept with someone. In the end, he couldn't hold out. Addison doesn't want a guy like him, and he doesn't deserve her, he says, shuffling off.

When she sees Alex studying later that night, though, Addison receives a second huge shock when he turns down her offer of a nighttime rendezvous. Their little soiree was great and all, but she's not his girlfriend, Alex tells her. Unable to find a man who'll give her what she wants, she walks out of the hospital pondering her place in the world.

Oh, and Cristina reluctantly chose the red velvet cake.