The two-part, gun-happy season finale sees the return of a bereaved husband, Mr. Clark, who had previously sued the hospital for wrongful death after his wife had a stroke and the doctors pulled the plug based on three-year-old documents. On a rampage, Clark fatally shoots Reed and Charles, wounds Alex, and nearly shoots Bailey before finally cornering Derek and shooting him in the chest. Later, as he is preparing to shoot Lexie, the SWAT team injures him. When he comes across Callie and Arizona in the pediatrics wing, Callie calmly provides him with bandages for his wound and asks him to leave. He does.

Cristina begins operating on Derek with Jackson, but Clark finds them and orders Cristina to let Derek die. When Owen tries to make a move, Clark shoots him. Meredith enters and pleads for Clark to shoot her instead, since she means so much to his three main targets: Derek, Lexie, and Richard. To fool Clark, Cristina and Jackson make it seem as if Derek dies on the operating table, much to Meredith's anguish. Once he leaves, they reattach the monitors and save Derek's life. Cristina asks Meredith to operate on Owen, which she does with April's help. When April notices that blood is soaking through Meredith's pants, Meredith declares matter-of-factly that she's having a miscarriage. Nooooo, McMiniDreamy!

Richard finds a way into the hospital and encounters Clark, who only has one bullet left and is unsure whether to use it on himself or Richard. Richard says that if he shoots him, he'll spend the rest of his life in jail, but if he shoots himself, he can be with his wife. Clark takes the latter option and shoots himself as the SWAT team storms in.
Credit: WENN Photo: The Doctors Gather in Seattle-Grace in Season 6, Episode 13, "State of Love and Trust"
What went down in Season 6 of Grey's? Hearts were repaired, hearts were broken, bullets flew, and doctors died. Here's our rundown, picking up right where Season 5 left off...
Alex and Lexie try to keep things casual at first, but they soon realize that they have feelings for one another. Once Alex receives and signs his divorce papers from Izzie, he says that he and Lexie are "a thing" and kisses her in public. But when Alex is critically injured in the finale, he mistakes Lexie for Izzie, apologizing for everything and begging Izzie to come back to him. Lexie, though obviously heartbroken, goes along with the act to comfort him.
Mark and Lexie move in together right before a girl shows up — Mark's prego daughter, Sloan. He invites Sloan to move in with him, which pisses Lexie off because he doesn't talk it over with her beforehand... and he evidently cares more about his daughter. Like any rational woman, Lexie moves out and sleeps with Alex. Complications with Sloan's pregnancy ensue, and Mark brings in Addison. The two of them have sex, natch. When both Mark and Lexie confess their indiscretions to each other, Mark ends the relationship. In the midst of this 'ship stress, Sloan gives birth, and Mark reluctantly helps her give the baby up for adoption. Mark returns to Lexie and tells her that he still loves her and wants to marry her, but Lexie turns him down since she's now happily with Alex.
Meredith and Derek are living in wedded bliss when Thatcher comes to the hospital with liver failure. Meredith decides to be his donor for Lexie's sake. She and Derek hit an awkward patch when she finally tells him that Richard has been drinking. Against her wishes, Derek uses this information to become Chief, but it's a steep learning curve. In the finale, Meredith finds out she's pregnant, but the chaos that of that day causes her to miscarry before she has a chance to tell Derek.
Bailey is probably hit the hardest by George's death, forcing her to realize that she's too emotionally invested in her former interns and needs to refocus her attention on her son. Her father arrives for Thanksgiving, and she struggles to win his approval. Later, an anesthesiologist named Ben Warren starts flirting with her, and they have a sexy fling. Go, Bailey!
The Mercy Westers invade Seattle Grace toward the beginning of the season and immediately clash with the original crew. Grey's focuses on four: April Kepner, Jackson Avery, Reed Adamson, and Charles Percy. April is fired early on for missing a critical symptom in a patient who died unnecessarily. Charles likes Reed, but Reed likes Alex. Jackson is revealed to be the grandson of a famous surgeon. He also has the hots for Cristina. Derek rehires April later on, and April develops a crush on him. She accidentally gets Derek shot in the season finale.
Cristina and Owen go to therapy together to work out their issues. When Cristina becomes frustrated that she has no mentor at the hospital, Owen brings in his army friend Teddy to be her cardiothoracic guru. After Teddy tests Cristina in a trial-by-fire surgery, Owen forces Teddy to admit that she was letting his feelings for him cloud her judgment. They agree that she should leave Seattle. Cristina is so desperate for Teddy to stay that she says Teddy can have Owen. After a period of uncomfortableness, in which Owen convinces Cristina that she can't value surgery over love, Teddy tells Owen that she misses her best friend; she wants to take back what she said because she likes being at Seattle Grace. But when another cardiothoracic surgeon shows up, Owen tells Derek that he could fire Teddy — mainly because he wants to end the love triangle. In the end, the other doctor leaves and Teddy keeps the position by default. (Of course she's gotta stay — Grey's has to keep things interesting!)
Callie and Arizona decide they're officially a couple, so much so that Arizona even says "I love you," and Callie says it back. But when Callie tells her she wants kids, Arizona — who isn't down with the family track — balks. The kids debate becomes a huge sticking point in their relationship. Things change quickly, however: After staring death in the face during the finale, Arizona tells Callie that they will have a big family.
Richard is having a tough time holding onto his position as Chief, especially after the rough merger with Mercy West. He starts drinking again. The board offers Richard early retirement, but Derek tells him that if he seeks help, he might be able to get his job back. Richard checks in to rehab and eventually returns to the hospital, proving his worth through successful surgeries.
Izzie and Alex are also enjoying the married life, though Alex is still worried for his wife's well-being. (After all, she did almost die after undergoing an operation to remove her brain tumor!) Still, she manages to convince Alex she's fine and returns to work. When she messes up and almost kills a patient, Richard fires her. Thinking that Alex was involved, she bizounces, leaving him distraught. When she finally returns, she tells Alex that she hasn't forgiven him for getting her fired, and Alex is too pissed to correct her. The next time she shows up at Seattle Grace, her brain scans come back clean and she and Alex celebrate the news. It's not all happy-happy-joy-joy, however: Alex tells her that while he loves her, he deserves better. Snap! Izzie leaves for a job in Tacoma... a mere 30 minutes south of Seattle.
George dies on the operating table, but Izzie survives. Everyone has their own way of dealing with the grief: some (ahem, Mer and Der) have rampant sex, others laugh riotously at his funeral. But the grief eventually hits all of them full-force — even steely Cristina.