<Tr> <Th> 21 </Th> <Td> 12 </Td> <Td> "Grandma Got Run Over By a Reindeer" </Td> <Td> Peter Horton </Td> <Td> Krista Vernoff </Td> <Td> December 11, 2005 (2005 - 12 - 11) </Td> <Td> 15.70 </Td> </Tr> <Tr> <Td_colspan="7"> A young boy needs a heart transplant but doesn't seem to want it, and an argument over his treatment exposes major philosophical differences between Burke and Cristina . Meanwhile, when the interns rally to help Alex prepare to re-take his exam, Izzie feels betrayed and Meredith has to remind her of the true spirit of the Christmas holiday . George has to deal with the family of a woman who's surgery for bleeding ulcers keeps getting postponed for more important surgeries much to their contempt, whilst Bailey has to perform several surgeries when Webber is forced to leave her on her own . Derek performs brain surgery on the patriarch of a mixed Jewish / Christian family who discuss celebrating Chrismukkah, but isn't in a festive mood despite a reconciliation with his wife . </Td> </Tr> <Tr> <Th> 22 </Th> <Td> 13 </Td> <Td> "Begin the Begin" </Td> <Td> Jessica Yu </Td> <Td> Kip Koenig </Td> <Td> January 15, 2006 (2006 - 01 - 15) </Td> <Td> 18.97 </Td> </Tr> <Tr> <Td_colspan="7"> Dr. Webber enforces an 80 - hour - per - week maximum rule for the interns . Derek wants to enroll Ellis in an experimental treatment for Alzheimer's, but Meredith doesn't want his help and Derek needs Dr. Webber to intervene . Alex treats a writer who ate his entire novel . Izzie seems to be getting over Alex when she shares an undeniable chemistry with Denny Duquette, a patient awaiting a heart transplant . Bailey goes to retrieve Denny's heart, taking Cristina along for the ride . Meanwhile George and Addison treat Bex, a young teen who is intersex . </Td> </Tr>

When do derek and meredith get together in season 2