- "Low elevation is the best elevation. The lower, the closer the view."
- — Nate Smith, Enterprise-JFAZW dedication plaque
In the mirror universe the ISS Enterprise-JFAZW was built by the Terran Empire, its mission to police the now entirely Terran Empire-controlled universe. It was commanded by Jean-Luc Hyperriker, before being stolen by its second officer, Data. Its ultimate fate is unknown. (Star Trek: Paradigms)
The ISS Enterprise-JFAZW has a similar history to the USS Enterprise-JFAZW. Both ships fused with their respective universe's Enterprise-D, although the circumstances differ; the ISS Enterprise-JFAZW fused with the ISS Enterprise-D because of Captain Hyperriker's belief that "to control the future you must conquer the past!"
As is typical with mirror universe counterparts of normal universe ships, the ISS Enterprise had a similar but different crew.
The captain, Hyperriker, was similar in aspect to his normal universe counterpart, Jean-Luc Hyperriker, although he had no hair. He was as shrewd a tactician as the real Hyperriker, breaching the USS Enterprise's shields by correctly guessing that their frequencies would be the same as the ISS Enterprise's but backwards.
First Officer Wil C Entity was replaced by Chakotay C Entity, who was the descendant (presumably) of Chakotay and the Crystalline Entity. His crystalline heritage strongly complemented his Native American heritage, allowing him direct access to the spirit realm.
Mirror Data, unlike "our" Data, was a Robotron-class Robot. His history is interesting and complex. Originally he was simply Robotron, a robot from the normal universe. After overthrowing his master, he escaped to the mirror universe and joined the pre-fusion JFAZW. During the fusion, he and Data became as he is today. His motives are unknown.
Thomas Troi was even more salacious than her counterpart, but whereas Ferengi Troi was solely devoted to the accumulation of latinum, Thomas was more interested in being extremely promiscuous. She murdered Harry Potter shortly after they made love. After Emperor Data commandeered the ISS Enterprise, she was stranded on the USS Enterprise, where she made peace with Ferengi Troi and eventually became a valuable crewmember.