<P> Carter later returns in the Season 15 episode, "The Beginning of the End", in which he rejoins the ER at County General . He explains to Cate Banfield that he is relocating to Chicago, and is looking to pick up some shifts . She agrees, after finding out that one of his teachers at the hospital was Mark Greene . He visits the Joshua Makalo Carter Center . At the end of the episode, it is shown that Carter is on dialysis because of amyloidosis developing from schistosomiasis which irreparably damaged Carter's remaining kidney . He is back in Chicago to be placed on the US transplant list . Working in the ER once again, he is shown to still be a good doctor with good judgment, but is still catching up with the latest medicines and techniques being used in the US . Eventually, his condition worsens, causing him to collapse while attending to a patient . While being treated by Dr Gates and Dr Morris, he goes into V - tach, but is brought back thanks to Morris's quick - thinking . He is transferred to Northwestern Medical Center . </P> <P> In the episode "Old Times", while a patient at Northwestern, he is visited by his mentor and good friend Dr Peter Benton, to whom he reveals that his marriage with Kem is going through a rough patch . In the same episode, Dr. Benton acts a back - seat driver and supervises the operation to make sure Carter is well taken care of . Later, Carter gets a new kidney and the transplant is a success . </P> <P> In "And In The End", the series finale, Carter uses his family fortune to finally open the Joshua Carter Center, a medical clinic for the underprivileged that fits into the plans he'd announced when his grandmother's will was read . Kem surprises Carter by attending the opening ceremony however she is seemingly uncomfortable around him . In a later conversation she tells him how she feels sad in Chicago because it reminds her of their son's death . As she leaves the clinics opening she okays Carter to call her to set up breakfast before she flies back to Paris . Carter indicates he might come back to County for good; however, this is potentially contradicted by his earlier idea that he will leave Chicago if that's what it takes to save his marriage . </P> <P> Early in the series, Carter's plots typically stayed in the realm of the ER . In a symbolic gesture of this transference, he was told by Mark Greene "you set the tone" on Dr Greene's last day in the ER . Dr. Greene had been told the same thing, by Dr. Morgenstern, in the pilot episode in Season 1 of the show . Dr. Carter, in turn, said the same thing to Dr. Archie Morris as Carter left the ER, although Morris did not understand the significance . </P>

Who does john carter end up with on er
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