<P> Izzie's cancer storyline received a mixed response from the medical community . Otis Brawley, chief medical officer at the American Cancer Society, commented that Izzie's treatment options were unrealistic . Whereas in the show she was offered the drug interleukin - 2, in reality the drug is never recommended to patients when melanoma has spread to the brain, as it can cause bleeding and strokes . Brawley explained that such patients would instead be offered radiosurgery . Conversely however, Tim Turnham, executive director of the Melanoma Research Foundation, praised Grey's Anatomy for bringing about greater public awareness of melanoma, stating: "We welcome the national spotlight Grey's Anatomy has created for melanoma and its efforts to encourage viewers to learn more about the importance of prevention, early detection and research ." </P> <P> The number in the "No. in series" column refers to the episode's number within the overall series, whereas the number in the "No. in season" column refers to the episode's number within this particular season . "U.S. viewers in millions" refers to the number of Americans in millions who watched the episodes live . The fifth season's episodes are altogether 1080 minutes in length . </P> <Table> <Tr> <Th> No . overall </Th> <Th> No. in season </Th> <Th> Title </Th> <Th> Directed by </Th> <Th> Written by </Th> <Th> Original air date </Th> <Th> U.S. viewers (millions) </Th> </Tr> <Tr> <Th> 79 80 </Th> <Td> </Td> <Td> "Dream a Little Dream of Me" </Td> <Td> Rob Corn Michael Pressman </Td> <Td> Shonda Rhimes </Td> <Td> September 25, 2008 (2008 - 09 - 25) </Td> <Td> 18.30 </Td> </Tr> <Tr> <Td_colspan="7"> A military doctor, Owen Hunt piques Cristina's interest due to his unorthodox treatment methods . Webber assigns Cristina to treat him when he notices that he's bleeding . Meredith and Derek attempt to work on their "happily ever after", and Meredith is plagued with a recurring nightmare where Derek dies . The ER is filled with car crash victims due to a snow storm . The attendings are stressed over Seattle Grace's ranking of number twelve . Derek's professional relationship with Rose takes a hit following their break up . Lexie is shocked to discover that Meredith has slept with George, especially due to her feelings towards him . Mark finds out about Lexie's feelings for George . An awkward atmosphere exists between Erica and Callie following their kiss . After an argument with Meredith, Cristina slips over and an icicle hanging overhead drops down and impales her . Cristina is annoyed when Webber orders her interns to treat her following her impalement . Owen ends up treating her, and after he turns down a job at the hospital, kisses her . Alex is annoyed with Izzie after he finds out that she told Meredith that she thought he was changing . Lexie is devastated when she discovers that George doesn't have feelings for her . Rose accidentally stabs Derek with a scalpel in the palm of his hand, and Derek is further frustrated when Webber takes treatment advice from Owen over Derek's patient . However, when the treatment threatens the patient's life, Callie freezes until Erica is able to encourage her to remember her research . Webber continues to push a hard line of trying to save every patient and berates Meredith when she is unable to do so . </Td> </Tr> <Tr> <Th> 81 </Th> <Td> </Td> <Td> "Here Comes the Flood" </Td> <Td> Michael Pressman </Td> <Td> Krista Vernoff </Td> <Td> October 9, 2008 (2008 - 10 - 09) </Td> <Td> 14.54 </Td> </Tr> <Tr> <Td_colspan="7"> There are leaks all over the surgical floor, but Webber is reluctant to remove any patients, until the roof in an operating room collapses on one . Meredith quits therapy explaining to Dr. Wyatt that she doesn't need it anymore and that her life is fine how it is . Webber holds a meeting with all of the doctors and explains the new teaching system . After the meeting he shakes up all of the doctors' specialties, taking them off their own cases and putting them on to different ones . Alex worries after his patient breaks hospital policy and injures himself while on his watch, and things get worse after he is electrocuted in a CT machine following water hitting the electrics . Meredith treats a bubbly girl with liver cancer, and Meredith is devastated when the cancer is worse than it seemed . Cristina helps Derek with a man who is in constant pain, but get annoyed when Derek tries using her to sway Meredith's opinion . George attempts to retake his intern exam, but can't because of the leaks . Derek attempts to make Izzie and Alex move out, forcing Izzie to ask Cristina to rent an apartment with her, only for Callie and Cristina to assume she was giving it to them . Erica explains to Callie why she doesn't want Mark to know about their relationship . </Td> </Tr> <Tr> <Th> 82 </Th> <Td> </Td> <Td> "Brave New World" </Td> <Td> Eric Stoltz </Td> <Td> Debora Cahn </Td> <Td> October 16, 2008 (2008 - 10 - 16) </Td> <Td> 14.57 </Td> </Tr> <Tr> <Td_colspan="7"> Meredith freaks out when Derek discovers her mother's old diary in the house while Callie frets as she prepares for her first official date with Erica . Meredith and George have to help Erica with a child patient who refuses surgery . Tensions are still high between Izzie and Alex, and things get worse after Alex takes Izzie's patient . George finds out he passed his intern exam and is now a resident, but he upsets Lexie when he begins celebrating with his friends instead of her . While in the clinic, Cristina goes into the dermatology department, and finds that it is completely different to the high - stress world that she knows . However, when she spends too much time in there, she ends up putting her patient's life at risk . </Td> </Tr> <Tr> <Th> 83 </Th> <Td> 5 </Td> <Td> "There's No' I' in Team" </Td> <Td> Randy Zisk </Td> <Td> Jenna Bans </Td> <Td> October 23, 2008 (2008 - 10 - 23) </Td> <Td> 14.21 </Td> </Tr> <Tr> <Td_colspan="7"> Bailey orchestrates a massive 12 - person simultaneous "domino" surgery with six separate kidney transplants . However, when it emerges that one patient is paying another for their kidney, and another finds out that her husband is having an affair with one of the donors, the surgery threatens to be cancelled . Alex and Izzie share a kiss . Callie begins avoiding Erica after not enjoying having sex with her and goes to Mark for advice . Lexie is hurt when she doesn't become one of George's interns . A rift comes between Meredith and Derek when their clinical trial is published and called the Shepherd method with no inclusion of Meredith . Following Derek's success, Mark is inspired to form his own clinical trial . </Td> </Tr> <Tr> <Th> 84 </Th> <Td> 6 </Td> <Td> "Life During Wartime" </Td> <Td> James Frawley </Td> <Td> Mark Wilding </Td> <Td> October 30, 2008 (2008 - 10 - 30) </Td> <Td> 15.05 </Td> </Tr> <Tr> <Td_colspan="7"> Dr. Owen Hunt returns to Seattle Grace, being named as the new Head of Trauma Surgery - all part of Webber's effort to raise the #12 ranking, and it works, raising Seattle Grace back to a Level I Trauma Center . Owen uses his unorthodox treatment and teaching methods, rubbing Izzie, Derek, Mark and Cristina the wrong way . In keeping with his spirit of raising the #12 rank, Webber has Bailey and Erica perform a tumor resection deemed impossible by many other hospitals . George has to deal with the fallout between him and Lexie . Izzie is annoyed when Alex inquires as to whether their new relationship is open or not . Callie continues to sleep with Mark as she tries to figure out who she really is after she is taken aback over Erica's openness about her homosexuality . </Td> </Tr> <Tr> <Th> 85 </Th> <Td> 7 </Td> <Td> "Rise Up" </Td> <Td> Joanna Kerns </Td> <Td> William Harper </Td> <Td> November 6, 2008 (2008 - 11 - 06) </Td> <Td> 15.63 </Td> </Tr> <Tr> <Td_colspan="7"> Izzie faces her past of Denny Duquette when the patient who was supposed to receive the heart that he got is admitted to the hospital . Erica finds out about the Denny / Izzie relationship for the first time, and blames Izzie for the patient's current condition . While talking over the situation with Callie, Callie takes Izzie's side, leading Erica to say she can't be "kind of" a lesbian, and she walks off . Bailey tells the residents about an upcoming solo surgery that one of them will be able to perform, creating a competition between them . All of the residents want to practice on patients, but are instead given an animatronic . When Lexie stumbles across a group of interns practicing procedures on themselves, she arranges a group of cadavers for them instead, but this is picked up on by the residents . Owen becomes displeased with the lack of empathy that the residents treat their patients with . Meanwhile, Derek talks Mark into helping him by sleeping with Cristina, so that she will stop calling Meredith in the middle of the night and Izzie begins to see hallucinations of Denny, and she can't figure out why . Derek and Bailey are concerned when their patient signs a DNR (Do Not Resuscitate) order . However, the pair have to stay with the patient's husband as he tries to resuscitate her following her heart stopping . </Td> </Tr> <Tr> <Th> 86 </Th> <Td> 8 </Td> <Td> "These Ties That Bind" </Td> <Td> Eric Stoltz </Td> <Td> Stacy McKee </Td> <Td> November 13, 2008 (2008 - 11 - 13) </Td> <Td> 15.59 </Td> </Tr> <Tr> <Td_colspan="7"> Sadie Harris (Melissa George), Meredith's best friend from college, arrives as a surgical intern at Seattle Grace Hospital, making Cristina jealous of their special friendship . A man wants his transplanted heart removed for spiritual reasons . Izzie continues to see visions of Denny, and Alex sees her struggling . After hearing the patient's beliefs about keeping things of the dead, Izzie asks Alex to burn Denny's sweater . The interns continue to practice on each other, however when Cristina sees Lexie's wounds she wrongly assumes that she is self - harming . After talking with Lexie, Meredith becomes concerned that Mark is getting feelings for her, and asks Derek to dissuade him from her . When Lexie is given praise over a stitch that Webber assumed that Cristina had taught her, Cristina discovers the interns' activities and orders it shut down . The doctors try to treat a man who was crushed in a dumpster, but Derek and Mark clash with Owen after he agrees to the patient's demands to stop treatment . It is revealed that Erica has quit her job as the Chief of cardiothoracic surgery at Seattle Grace Hospital and moved away, leaving Callie devastated and Webber baffled . In her place, a renowned heart surgeon, Dr. Virginia Dixon is called in, but Bailey and Alex become concerned over her mental well - being . When Bailey manipulates Dixon to follow a patient's wishes, Dixon decides not to return to the hospital . Cristina discovers that Callie and Erica had been dating . </Td> </Tr> <Tr> <Th> 87 </Th> <Td> 9 </Td> <Td> "In the Midnight Hour" </Td> <Td> Tom Verica </Td> <Td> Tony Phelan & Joan Rater </Td> <Td> November 20, 2008 (2008 - 11 - 20) </Td> <Td> 15.74 </Td> </Tr> <Tr> <Td_colspan="7"> Izzie's visions of Denny become more intense as they have sex and argue with each other . The interns open up Sadie to remove her appendix, but when things get complicated, they have to approach Cristina and Meredith for help . When Webber finds out about the appendix operation, tensions flare between Cristina and Meredith . The atmosphere between Owen and Cristina becomes awkward following their recent kiss . Callie becomes a patient after receiving a nose fracture when she is punched in the face by a patient who is suffering from severe night terrors, and Mark becomes concerned about the patient's young daughter . Alex has to deal with a patient who needs a fecal transplant after she made herself ill from self - medicating . George finally finds out about Lexie's feelings for him, just as Mark begins to develop his own feelings for her . Bailey begins to doubt whether she wants to remain as a general surgeon . </Td> </Tr> <Tr> <Th> 88 </Th> <Td> 10 </Td> <Td> "All By Myself" </Td> <Td> Arlene Sanford </Td> <Td> Peter Nowalk </Td> <Td> December 4, 2008 (2008 - 12 - 04) </Td> <Td> 15.15 </Td> </Tr> <Tr> <Td_colspan="7"> Cristina is awarded the first solo surgery among the residents, but she has to relinquish it and choose her replacement; Mark performs a cutting - edge procedure to restore a patient's speech, impressing Lexie in the process . Callie cannot figure out if Sadie is flirting with her or just being friendly . Mark desperately tries to get Lexie out of his head, but after some prompting from Sadie, Lexie seduces him and they sleep together . Dixon returns to the hospital, and Webber assigns Cristina to her services, hoping that she will impress Dixon enough to become the new head of cardiothoracic surgery . A pair of teenage girls who won't stop arguing show up in the E.R. after crashing their parents' car, annoying the doctors present . George begins to suspect something is wrong with Izzie after he sees her talking to herself, and is told that she hasn't properly attended the clinic in weeks . Cristina and Owen share another kiss after he takes her to the boiler room to comfort her for losing the solo surgery . </Td> </Tr> <Tr> <Th> 89 </Th> <Td> 11 </Td> <Td> "Wish You Were Here" </Td> <Td> Rob Corn </Td> <Td> Debora Cahn </Td> <Td> January 8, 2009 (2009 - 01 - 08) </Td> <Td> 13.71 </Td> </Tr> <Tr> <Td_colspan="7"> Meredith and Cristina are still at odds with each other, but after reflecting on her past with Sadie, Meredith is inspired to try and make things right . George has a young patient who put her life on hold because she keeps having accidents . Mark and Callie both try and fight their respective feelings for Lexie and Sadie, but after seeing George's patient take her life by the reins following her surgery, Mark gives in to his feelings for Lexie . While Webber mourns the sudden death of the pediatric surgeon, Bailey is unhappy with the new one, Dr. Arizona Robbins, as they clash over the best course of treatment for a patient that Bailey has formed an emotional bond with . Derek and Meredith disagree about the treatment of a death - row prisoner . Izzie tells Alex about Denny, but she is put off by his lack of empathy toward the situation . First appearance of Dr. Arizona Robbins . </Td> </Tr> <Tr> <Th> 90 </Th> <Td> 12 </Td> <Td> "Sympathy for the Devil" </Td> <Td> Jeannot Szwarc </Td> <Td> Jenna Bans </Td> <Td> January 15, 2009 (2009 - 01 - 15) </Td> <Td> 12.95 </Td> </Tr> <Tr> <Td_colspan="7"> Derek still doesn't approve of Meredith showing sympathy for the death - row prisoner, and things get worse when the prisoner offers his organs to Bailey and Arizona's patient . Alex is annoyed by Arizona's seeming lack of empathy when the pair of them go to harvest a young child's organs . Callie treats a short man who underwent a risky procedure for two extra inches . Following the surgery, Mark gives Callie some advice after hearing how afraid she is of getting hurt again . Meredith is worried about meeting Derek's mom (Tyne Daly) for the first time, and Mark worries that his relationship with Lexie will be exposed . Owen asks Cristina out, but he ruins the date after getting drunk following Derek's mom asking him about his time in the field . Izzie breaks up with Denny, and Alex asks Izzie to meet his parents . </Td> </Tr> <Tr> <Th> 91 </Th> <Td> 13 </Td> <Td> "Stairway to Heaven" </Td> <Td> Allison Liddi - Brown </Td> <Td> Mark Wilding </Td> <Td> January 22, 2009 (2009 - 01 - 22) </Td> <Td> 14.25 </Td> </Tr> <Tr> <Td_colspan="7"> Denny continues to appear to Izzie despite her having broken up with him, and as Izzie tries to figure out why he is still there she comes to realize that she is sick . In the meantime, matters around the death - row patient get really rough while Bailey's patient continues to get worse, causing Bailey to try and get Derek to stop treating the prisoner, and Webber to try and convince the wife of a brain - dead patient to donate her husband's organs . Lexie injures Mark during sex, leading to an embarrassing situation involving Owen and Callie . Owen tries to make amends with Cristina following his actions the previous night . Meredith and Cristina finally make amends after Meredith goes to witness the prisoner being put to death . </Td> </Tr> <Tr> <Th> 92 </Th> <Td> 14 </Td> <Td> "Beat Your Heart Out" </Td> <Td> Julie Anne Robinson </Td> <Td> William Harper </Td> <Td> February 5, 2009 (2009 - 02 - 05) </Td> <Td> 15.20 </Td> </Tr> <Tr> <Td_colspan="7"> Bailey is promoted to attending by Webber, but when she finds herself having another child - patient, she seriously doubts herself . However, Dixon and Arizona both suggest that Bailey will make a good pediatric surgeon . Webber treats a couple who tried to spice up their sex - life . Derek prepares to propose, but he decides to postpone the proposal when he receives a call from Addison . Dixon has a nervous breakdown when her patient's parents try to hug her, causing Bailey and Cristina to give her a special treatment . Owen and Cristina find themselves engaged in old - fashioned courting, but things take a turn when Owen sees someone from his past . Arizona kisses Callie after she sees her being upset . Meredith, Lexie and Callie treat a man who was accidentally ran over by his pregnant wife, while simultaneously trying to keep her calm so that the baby isn't affected . Izzie has the interns unknowingly do tests on her, as she tries to figure out what is wrong with her, but Sadie confuses her results with that of another patient . Lexie wants to make her relationship public with Mark, but Mark confides in Callie that he wants to end things out of respect for Derek . </Td> </Tr> <Tr> <Th> 93 </Th> <Td> 15 </Td> <Td> "Before and After" </Td> <Td> Dan Attias </Td> <Td> Tony Phelan & Joan Rater </Td> <Td> February 12, 2009 (2009 - 02 - 12) </Td> <Td> 15.70 </Td> </Tr> <Tr> <Td_colspan="7"> <P> Addison (Kate Walsh) arrives with her brother Archer (Grant Show), who has worms in his brain . While Addison is there, she discovers the truth about Mark and Lexie . Cristina learns of Owen's pre-Iraq past . Cristina and Webber treat a man who wants to keep his cancer a secret from his daughter, who is Owen's ex-fiance. Bailey considers a pediatric surgery fellowship . Izzie enlists the help of the attendings and her fellow residents in a game to boost camaraderie amongst the interns, and George finds out that Sadie is behind with her skills . When he reports her to Webber, she quits the program . Meredith's pregnant patient is annoyed when she learns that her surgery has been postponed because of Addison's brother . Alex begins to suspect that something is wrong with Izzie when she begins experiencing short - sightedness . Derek and Mark spend the evening reminiscing on their med school days with Addison, Naomi Bennett, and Sam Bennett . </P> This episode begins a crossover with Private Practice that concludes on "Ex-Life". </Td> </Tr> <Tr> <Th> 94 </Th> <Td> 16 </Td> <Td> "An Honest Mistake" </Td> <Td> Randy Zisk </Td> <Td> Peter Nowalk </Td> <Td> February 19, 2009 (2009 - 02 - 19) </Td> <Td> 15.39 </Td> </Tr> <Tr> <Td_colspan="7"> Addison, Meredith and Alex become concerned with Derek when he plans to take extreme measures in order to save a patient's life . Cristina annoys a senior doctor, Dr. Margaret Campbell, when she criticizes her treatment methods, however when Cristina finds a more serious issue with the patient, she reports Campbell for negligence . Callie is turned down by Arizona when she discovers that Callie is still figuring out her sexuality . Bailey has trouble getting a decent letter of recommendation from Webber . Izzie gets the news about her false test - result and investigates the matter further . Derek and Mark get in a public fight after Derek loses a patient, and Mark tells him that he has been seeing Lexie . </Td> </Tr> <Tr> <Th> 95 </Th> <Td> 17 </Td> <Td> "I Will Follow You Into the Dark" </Td> <Td> James Frawley </Td> <Td> Jenna Bans </Td> <Td> March 12, 2009 (2009 - 03 - 12) </Td> <Td> 13.54 </Td> </Tr> <Tr> <Td_colspan="7"> Izzie walks the interns through diagnosing Patient X after receiving her troubling test results . After receiving the diagnosis, Izzie decides to speak to Cristina about it . Bailey and Meredith perform a surgery where they remove a woman's stomach to protect her from a very aggressive form of stomach cancer that runs in her family . Owen accidentally injures Cristina when she startles him . Owen, Alex and Arizona treat a high school marching band player with seizures, but Alex and Arizona clash when Alex suspects that the patient is suffering from something different . Derek refuses to work after killing the patient from the previous episode . Webber tells Meredith that Derek was planning to propose to her in the hopes that it will encourage her to try and bring Derek back to work . Callie tries hiding from Arizona after her rejection, but Arizona eventually asks her out on a date . Webber and Bailey continue to clash over Bailey wanting to move into pediatric surgery, leading to Adele having to come and intervene . </Td> </Tr> <Tr> <Th> 96 </Th> <Td> 18 </Td> <Td> "Stand By Me" </Td> <Td> Jessica Yu </Td> <Td> Zoanne Clack </Td> <Td> March 19, 2009 (2009 - 03 - 19) </Td> <Td> 14.36 </Td> </Tr> <Tr> <Td_colspan="7"> Izzie doesn't want to fight the brain tumor, despite Cristina's efforts to help her . This starts affecting Cristina's surgery performance so she tells Bailey and Alex, who subsequently inform the others, and Izzie is admitted at the hospital as a patient . The surgeons are all busy preparing for a facial transplant surgery . However Meredith and George are annoyed when they find out that they're not playing any part in the surgery . The pair also try to mediate a fight between two interns caused by a love triangle. Bailey becomes worried when she sends Callie and Owen out to talk to Derek and neither return . Meanwhile, Webber stresses over Derek's absence and how to dissuade him from quitting, and Meredith worries that Derek has dumped her . Lexie grows tried of the other interns gossiping about her relationship with Mark . </Td> </Tr> <Tr> <Th> 97 </Th> <Td> 19 </Td> <Td> "Elevator Love Letter" </Td> <Td> Edward Ornelas </Td> <Td> Stacy McKee </Td> <Td> March 26, 2009 (2009 - 03 - 26) </Td> <Td> 15.81 </Td> </Tr> <Tr> <Td_colspan="7"> Derek prepares for Izzie's surgery to remove her brain tumor, with the attention of the hospital rising . However, Meredith, Cristina, Alex and George all avoid Izzie before her surgery . Owen has another PTSD episode that leads him to strangle Cristina, which traumatizes her and leads to her breaking up with him . Derek offers to help Owen get over his PTSD . Alex and Lexie are off put by their patient's family's eagerness for the patient to die . Callie is filled with regret because of her previous animosity toward Izzie . George is hurt because Izzie chose to confide in Cristina instead of him . Alex begins blaming himself for not picking up on Izzie's symptoms earlier . Derek proposes to Meredith in the elevator . </Td> </Tr> <Tr> <Th> 98 </Th> <Td> 20 </Td> <Td> "Sweet Surrender" </Td> <Td> Tony Phelan </Td> <Td> Sonay Washington </Td> <Td> April 23, 2009 (2009 - 04 - 23) </Td> <Td> 13.22 </Td> </Tr> <Tr> <Td_colspan="7"> Bailey learns of the heart - wrenching practices in pediatrics . Callie's father (Héctor Elizondo) visits her at work, and after learning of her relationship with Arizona, he tries to take her home (by transferring her to another hospital, in exchange for a donation to the hospital), but ends up having no success . Izzie undergoes chemotherapy as she begins to plan Derek and Meredith's wedding . Meredith is shocked when she discovers that Derek has chosen Webber to be his best man . Alex is in trouble with Owen after a patients attempts suicide on his watch, while Owen tells George that his specialty is definitely trauma surgery . Derek and Mark continue to argue with each other following their fight, leading to Lexie becoming concerned when they have to treat a patient together . However, the pair manage to patch things up when Derek is impressed by Mark's surgical skills . Owen begins receiving therapy from Dr. Wyatt to help with his PTSD . </Td> </Tr> <Tr> <Th> 99 </Th> <Td> 21 </Td> <Td> "No Good at Saying Sorry (One More Chance)" </Td> <Td> Tom Verica </Td> <Td> Krista Vernoff </Td> <Td> April 30, 2009 (2009 - 04 - 30) </Td> <Td> 13.94 </Td> </Tr> <Tr> <Td_colspan="7"> Izzie's mother comes to visit her, but Izzie quickly becomes annoyed by her . Izzie then begs Bailey to lie to her mother about her test results so that she will leave . Bailey does so and the plan works, but Bailey then reveals to Izzie that she will need further surgery . Callie is dealing with the loss of her trust fund, which her father took away when he found out about her relationship with Arizona . Meredith and Lexie's father, Thatcher, shows up . He's recovering and getting sobered up, but Meredith's not able to forgive him and gets caught up in drama with Webber over how to handle a case involving a man shot by his young daughter . Meanwhile, Owen, George and Cristina try to save the man, but Cristina becomes annoyed at the amount of attention that Owen is giving George . Mark gains the courage to meet Thatcher . Mark and Callie treat an environmentalist who broke all of her limbs after falling out of a tree . </Td> </Tr> <Tr> <Th> 100 </Th> <Td> 22 </Td> <Td> "What a Difference a Day Makes" </Td> <Td> Rob Corn </Td> <Td> Shonda Rhimes </Td> <Td> May 7, 2009 (2009 - 05 - 07) </Td> <Td> 15.33 </Td> </Tr> <Tr> <Td_colspan="7"> As Meredith, Derek and all of their friends prepare for the big wedding, a group of college students, injured in a car crash as they were heading to their graduation ceremony, are admitted to the ER . Meanwhile, Izzie fears the worst when it is discovered that she has another brain tumor . Owen attempt to rekindle his relationship with Cristina . Callie and Arizona have a fight over their previous date, while George learns the consequences of being a trauma surgeon . Meredith performs her first solo surgery, but she is annoyed by Webber's observations . Following Izzie's brain tumor news, Meredith decides to give hers and Derek's wedding to Izzie and Alex . </Td> </Tr> <Tr> <Th> 101 </Th> <Td> 23 </Td> <Td> "Here's to Future Days" </Td> <Td> Bill D'Elia </Td> <Td> Allan Heinberg </Td> <Td> May 14, 2009 (2009 - 05 - 14) </Td> <Td> 15.58 </Td> </Tr> <Tr> <Td_colspan="7"> Izzie spends time with a fellow cancer patient and contemplates whether or not to undergo a risky surgery, as Mark is ready to take his relationship with Lexie to the next level by asking her to move in . Callie and Owen argue over a patient who desires a leg amputation . The situation makes Owen reassess his place at Seattle Grace, leading him to visit his mother for the first time since he came back from the war . George, after working on the case with Owen, decides to join the army . Webber attempts to tempt Bailey back into general surgery with a piece of fancy new equipment, which draws him into a conflict with Arizona . Izzie undergoes surgery after signing a DNR chart . </Td> </Tr> <Tr> <Th> 102 </Th> <Td> 24 </Td> <Td> "Now or Never" </Td> <Td> Rob Corn </Td> <Td> Debora Cahn </Td> <Td> May 14, 2009 (2009 - 05 - 14) </Td> <Td> 17.12 </Td> </Tr> <Tr> <Td_colspan="7"> Izzie finally wakes up from surgery, only for everyone to realize that her short - term memory has gone bad; this worries Alex to a point where he yells at her, only to have her remember everything he said . Arizona offers Bailey the peds fellowship, but Bailey struggles to accept it after Tucker threatens to leave her if she takes it . News spreads about George joining the army . The doctors (besides Izzie) focus on a "John Doe" who jumped in front of a bus to save a woman's life . Derek and Meredith plan to go to city hall to get married, only to be so busy that they write their vows on a post-it note . After getting advice from Meredith, Cristina tells Owen that she loves him and reunites with him . Mark tries to avoid Lexie after she rejected his proposal to move in together . Bailey and Callie organize an intervention to talk George out of joining the army . Arizona and Callie argue over George's decision to join the army when Arizona is supportive of it . However, when "John Doe" writes "O-O - 7" on Meredith's hand, she realizes that it's George . Izzie loses consciousness again . </Td> </Tr> </Table> <Tr> <Th> No . overall </Th> <Th> No. in season </Th> <Th> Title </Th> <Th> Directed by </Th> <Th> Written by </Th> <Th> Original air date </Th> <Th> U.S. viewers (millions) </Th> </Tr>

When do meredith and derek get back together season 5