11. 5x10 "Wish You Were Here" (OAD 1/8/09)
The chief pediatric surgeon has a heart attack and dies, and Arizona Robbins is brought in. She's young and perky and wears shoes with wheels on them. Bailey doesn't like her, but comes to respect her.
Cristina and Meredith are still fighting because Meredith didn't stand up for Cristina when she got in trouble for the interns doing procedures on each other. Sadie reminds Meredith that the two of them had a fight like this once and they never really recovered from it and she should apologize to Cristina.
On Izzie's birthday she tells Alex about Denny, but he doesn't seem too concerned. Izzie doesn't want to make a wish because she has everything she'd ever wanted, meaning Alex and Denny.
12. 5x11 "Sympathy for the Devil" (OAD 1/15/09)
Derek's mother comes for a visit and Izzie coaches Meredith on how to be a girlfriend that mothers like. Mark hides from her, but when she corners him he admits to sleeping with Lexie. She talks to Lexie and decides that she is a good person and tells Mark that she likes her.
Meredith tells Mrs. Shepherd that she's a fraud and has been acting.
Mrs. Shepherd gives Derek a wedding ring and says that his father wanted him to have it for the right girl. He is surprised because she'd just met Meredith, but she says she can tell.
Owen asks Cristina on a date and then shows up late and drunk. He says it's been 5 years since he's dated and he just wanted to take the edge off.
13. 5x12 "Stairway to Heaven" (OAD 1/22/09)
Izzie tells Denny to go. He keeps saying he's here for her. She finally figures out that she is dying and he's there to take her away. She says no and pushes him away.
Meredith fights with Derek and Cristina about a death row patient. Meredith shows him compassion, but Derek is angry because a man like him killed his father. Meredith goes to the execution because the man asked her to and Derek picks her up there. She's crying and she won't stop, so he goes and gets Cristina.
A dying boy needs a transplant and Bailey tries to get it from the death row patient, asking Shepherd to kill him. Webber coerces a woman into donating her husband's organs. Bailey tells Webber that she'd crossed a line. He says he did too and then she begins to cry.
14. 5x13 "Beat Your Heart Out" (OAD 2/5/09)
Izzie tries to draw her own blood, but can't do it, so she has her interns "practice" on her. Her tests reveal that she is anemic.
Derek is ready to propose to Meredith. Meredith is freaked out because when she comes near, conversation stops. Mark helps Derek decorate Meredith's room. Derek gets a call from Addison, cleans the room, and leaves.
Dr. Dixon has a panic attack and tells Cristina to hug her to slow down her nervous system. Owen has a panic attack, which Cristina helps him through with the same technique.
Lexie tells Mark that she doesn't want to keep their relationship secret anymore.
Arizona sees that Callie is sad, and kisses her.
15. 5x14 "Before and After" (OAD 2/12/09)
Izzie holds a contest for the interns and George figures out that Sadie does not know things that she should know. He tells her to go to the chief or he will, and she goes in and quits. Lexie wins the contest.
Addison brings her brother, Archer, to the hospital because he's got brain parasites and she wants Derek to operate. Derek saves Archer's life.
The fiance with whom Owen broke the engagement is in the hospital with her sick father. Cristina finds out that she thought he was still in Iraq and that his mother still thinks he's in Iraq. He tells Cristina that they want the old Owen and he's not here anymore. Cristina is the only one who doesn't look at him like he's a ghost.
16. 5x15 "An Honest Mistake" (OAD 2/19/09)
The interns switched the labs the day Izzie had them check her out. She checks herself over and then goes to the dermatologist. Then she has the interns look at her labs, saying they are for Patient X.
Cristina works with an older doctor whom she believes needs to retire. Owen tells Cristina that even though she was right, she was a bully about it.
Derek and Addison disagree over their patient. Derek tries to save mother and baby by removing parts of the mother's brain. Addison says that the woman is virtually brain dead and she needs to deliver the baby. Addison manages to save the baby and the woman dies.
Upset with losing his patient, Derek punches Mark when Mark says he's in a relationship with Lexie.
17. 5x16 "I Will Follow You Into the Dark" (OAD 3/12/09)
The interns diagnose Patient X with brain cancer and give her a 5% survival rate. Izzie knows that they are right. She wants to talk to Cristina because she's a robot and won't be too torn up by it, so Cristina takes her to the special lower floor vent and Izzie tells her.
Arizona asks Callie out on a date.
Derek won't come to work after making a mistake that killed a woman. The chief tells Meredith to get him back and that he was going to propose. Meredith goes to his trailer, where he is drunk and hitting cans with a baseball bat and saying he's done operating. She says she knows about the ring and he pulls it out and hits it with the bat.
Lexie apologizes to Mark for breaking him, and Mark says that she didn't break him, she put him back together.
18. 5x17 "Stand by Me" (OAD 3/19/09)
Cristina tells Bailey and Alex about Izzie's cancer after Izzie refuses treatment.
Bailey sends Callie to get Derek. She talks to him about a mistake that she'd made that caused her patient to die. He gives her a beer. When Callie doesn't return, Bailey sends Owen. He talks about a loss and Derek gives him a beer. Bailey sends the chief and Derek tries to kick him out, but he says that when this is over Derek will need friends and Webber will be there for him.
Meredith drives over. Derek asks if she will love him if he's not a surgeon and she says no because Izzie has cancer and he's one of only about twenty who can save her and she wouldn't be able to respect someone who could give up that kind of gift. She leaves him with Izzie's scans.
19. 5x18 "Elevator Love Letter" (OAD 3/26/09)
Owen chokes Cristina in his sleep. She tells Owen that it's okay and they have sex, but lying there after, Cristina says that she is sorry but she can't do this after all.
Derek performs a successful surgery on Izzie.
When Meredith goes to leave, Webber won't let her get on the elevator. The other opens and Derek is inside with brain scans posted all over the elevator walls. He goes through each one talking about what Meredith did in each one and how it brought them closer together. He says he won't ask her a question but he wants to spend the rest of his life with her. She says she wants to spend the rest of her life with him. She goes home and tells Cristina that she is engaged.
20. 5x19 "Sweet Surrender" (4/23/09)
Izzie tries to go through her treatments like they are no big deal. Meredith tells Izzie she can plan Meredith's wedding, hoping to get her mind of off her illness. Meredith is sorry when Izzie wants her to try on a bunch of different wedding dresses.
Derek and Mark have an argument over a patient, but Derek comes to see that Mark really is a good doctor.
Lexie is stress eating over the tension between Mark and Derek.
Izzie waits until everyone leaves the room, and then throws up.
Callie's father shows up and gives her an ultimatum. If she stays with Arizona, he will cut off her trust fund. She decides to stay with Arizona.