He thinks he can cure Zimmerman. But this would involve transmitting himself back with this month's data stream, since Alpha Quadrant doctors don't know about this stuff. Janeway denies permission, then relents when the Doctor notes that everyone he has ever treated ultimately owes Zimmerman.

Such transmission requires reducing the Doctor's page weight considerably. Seven handles these operations, removing his operatic singing ability and other unnecessary capacities. The Doctor only reluctantly agrees to this, because he hopes not only to cure Zimmerman but to impress his template-father culturally.

The Doctor arrives at Jupiter Station for a 1-month stay. Barclay introduces him to Zimmerman, who greets him with undisguised contempt. The Doctor is an obsolescent Mark 1 hologram, a model that has since been put to work scrubbing plasma conduits on waste-transfer ships. Go sightseeing on Jupiter's third moon, the angry genius taunts his creation.

Zimmerman notes that more recent holograms, as well as "real doctors," have failed to cure him. He reluctantly agrees to an exam, but when the Doctor deactivates a holographic talking iguana, tempers fly. Forcibly transferred to the next room, the Doctor angrily swats a holographic insect.

Shortly thereafter, the Doctor rages to Barclay and Haley, Zimmerman's assistant, that he's leaving. His latest scan indicates Zimmerman is a "Vulcan marsupial" -- a prank by the brilliant, belligerent innovator.

Barclay, perceiving that the doctor-patient relationship is not going well, asks Deanna Troi to come help. She's reluctant to leave the Enterprise, but says she'll ask Captain Picard for leave.

Jupiter Station. Zimmerman receives a massage from an exotic-looking woman while complaining about the Doctor. He's understandably enraged to deactivate the masseuse's holographic disguise and find she's really the Doctor, trying a new tack. He shouts, threatens, suggests the Doctor go work in a "Ferengi night club."

Deanna walks in. Seeing the two bald men, one considerably older-looking, she asks which is Zimmerman. They appear understandably surprised at her lack of the basic information she needs to do her job.

She tries to get each to see the other's perspective. It seems to work for a moment, but then further bickering erupts, and the exasperated counselor proclaims they're both jerks. "Jerks," echoes the iguana.

Things are getting even worse. The Doctor spends his time in the holodeck running Barclay's Voyager simulation. Haley brings some ice cream to Deanna and Barclay. Deanna, using her empathic skills, realizes Haley is a hologram.

The attractive executive assistant says yes, she was programmed 9 years ago. Deanna notes that makes her even more obsolescent than the Doctor, yet Zimmerman seems to like and respect Haley.

There is discussion. As it emerges, Zimmerman was indeed proud of the Mark 1 emergency medical holograms, but they didn’t live up to Starfleet's expectations -- particularly embarrassing, since he modeled those holograms, in looks and behavior, after himself. He tried to fix them, but then gave up and developed new medical holograms.

Meanwhile, Zimmerman, alone and still dying, is dictating his will. He bequeaths his "Trojan Horse" project -- the latest infiltration research -- to Barclay, the only engineer he trusts to complete it. Barclay also gets his holographic art collection, including that 21^st century masterpiece "Woman in Four Dimensions".

He requests Starfleet keep his assistant Haley running after his death, for as long as this research facility exists. "She's been as real to me as anyone I've ever known," he says with growing somberness.

"Not that I've known many people. I've created most of my friends."

Suddenly he gasps in physical pain. He recovers a bit, and starts working on finding new homes for his holographic pets.

Barclay says it's a disastrous consequence of being transmitted 30,000 light-years. The Doctor's primary matrix is destabilizing, but "there's nothing I can do," the engineer says, grimly.

Informed of this, Zimmerman says "Good riddance to bad photons," but then agrees to work on the problem, after Haley reminds him that she, too, is a hologram. The Mark 1 needs his creator, she says.

Zimmerman works on fixing the Doctor, but also wants to add different personality features. The Doctor doesn’t want that, prompting an outburst from his creator, who rails against how the first EMH units were derided as emergency medical "hotheads" and "extremely marginal housecalls."

He tried to have them decommissioned, but Starfleet in its wisdom insisted on using them for garbage duty instead.

Imagine the humiliation. Some 675 Mark 1s out there, scrubbing plasma -- each one with his face.

Zimmerman lies down, exhausted. The Doctor moves to examine him. At least, there's one Mark 1 doing what he was designed for, says Zimmerman. After some more discussion, he agrees to be treated, using the Borg implant-derived therapy the Doctor recommends.

The Doctor meanwhile is fixed. Indeed, his matrix problem was a ruse, created by Barclay, to build trust between the two bald men.

Soon, the treatment is working. The Doctor will have to go back to Voyager soon, but he's optimistic that Zimmerman will make a full recovery. And relations have, in a largely unspoken way, been repaired.

Before the Doctor leaves, he takes a few snapshots of Jupiter Station, as mementos.