<P> Rebecca returns and she and Alex sleep together before she goes back to her husband . Alex has a brief relationship with intern Lexie Grey (Chyler Leigh), but chooses to be with Rebecca when she returns and tells him she is pregnant . After Rebecca attempted suicide, Izzie convinces Alex to admit her for psychiatric help due to Rebecca's hallucinations of her pregnancy . Alex later breaks down in Izzie's arms, and the two kiss . </P> <P> Later in their relationship, Izzie begins hallucinating about Denny, and uncovers the fact she has metastatic melanoma (Stage IV) with an estimated chance of 5% survival . It is revealed that Izzie's hallucinations of Denny are, in fact, caused by her tumor . Alex is shocked by the news, but finds the strength to stay by her side . Izzie plans a wedding for Meredith and Derek, but when Derek finds Izzie has another inoperable tumor in her brain, they give the wedding to Izzie and Alex, who marry in front of all their friends . Izzie debates whether or not she should undergo a risky surgery to remove her tumor and Alex supports her, but eventually insists that she should have the surgery . Alex performs CPR on Izzie after she flatlines . </P> <P> Izzie regains a heartbeat but is soon fired leaving Alex a Dear John letter and no clue as to her whereabouts . She later returns to the hospital and says to Alex, thinking he had a hand in getting her fired, that she could not forgive him for talking to the Chief . Alex says he could not forgive her either for not giving him the benefit of the doubt and leaving without talking to him first . Alex re-kindles an old flame with Lexie . Alex seems to have recently found that his calling is actually Peds and not Plastics as he had decided in the earlier seasons . Seeing Alex's ability to handle child patients, Dr. Arizona Robbins shows an interest in mentoring him for that specialization . Alex's brother Aaron comes to Seattle Grace for surgery, and lots of painful memories resurface because of this . Meredith discovers Alex, along with Aaron and their sister Amber, had been in foster care for five years when their mother could not take care of them . Alex is also served with divorce papers from Izzie . Alex is shot in the hospital by a deceased patient's husband, but survives with the help of Lexie and Mark . While undergoing treatment, he mistakes Lexie for Izzie . </P> <P> Following the shooting, Lexie has a mental breakdown in front of Alex and he walks away . Dr. Bailey bars Alex from surgery until he has the bullet removed, which he later allows her to do . Alex realizes that his passion lies in Pediatric Surgery . He is further shown to be excellent with children, comforting with a young patient while growing her a new trachea . He immediately gets on the wrong side of new Pediatric attending Stark while Arizona is on leave . Alex then attempts to sleep with virgin April Kepner after visiting his mom in Iowa when his brother was diagnosed schizophrenia . Alex and Meredith perform an emergent surgery on a young boy by themselves during the night shift, dealing with the angry fallout from Stark (who would not answer his pager) but gaining the wordless approval of the Chief . Alex is thrilled when Arizona returns from Africa and hopes she will come to work for the hospital again . In the meantime, Alex falls for the new OBGYN attending, Lucy Fields, and they start a relationship after she kisses him . Alex finds out about Meredith sabotaging her Alzheimer's clinical trial and rats her out in attempt to get Chief Resident . </P>

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