| File:Neural parasite.jpg | |
| Caption: | A neural parasite. |
| File:Neural parasite quinn.jpg | |
| Caption: | A parasite infiltrated Gregory Quinn. |
| File:Alien parasite mother.jpg | |
| Caption: | The mother creature. |
Neural parasite (or blue gill) aliens attempted to infiltrate the Federation's Starfleet Command in 2364, by physically infiltrating high-ranking admirals within the organization. Persons who fell victim to infiltration included Admiral Gregory Quinn, Admiral Aaron, and Admiral Savar.
Admiral Quinn suspected that something was wrong at the highest levels of Starfleet Command in mid-2364. Seeking allies he could trust, he ordered Lieutenant Commander Dexter Remmick to investigate Captain Jean-Luc Picard to determine his trustworthiness. Remmick's investigation found that, despite a sense of over-familiarity among the Enterprise-D's bridge crew, Picard was above reproach. Quinn told Picard of his suspicions and that he wanted to promote Picard to Admiral, so he could take over as Commandant of Starfleet Academy. Picard turned down the offer, believing he could serve Quinn better by remaining as captain of the Enterprise. (TNG: "Coming of Age")
Other high-ranking officers had their own suspicions. Admiral Norah Satie was instrumental in discovering the conspiracy. (TNG: "The Drumhead") Captains Walker Keel, Rixx and Tryla Scott noticed a pattern of unusual orders and activity coming from Starfleet Command. Officers they had known for years were, in Keel's words, suddenly "bluffing their way through talk of old times," Starbase 12 was mysteriously evacuated for two days without explanation and Onna Karapleedeez, Ryan Sipe and McKinney had all died under mysterious circumstances.
Quinn and Scott fell victim to the parasites, both becoming hosts, and Remmick became host to the parasites' mother creature. However, Captains Keel and Rixx were unaware of this and called Picard to a meeting on Dytallix B via a Code 47 signal. They warned Picard of the threat, and to watch his back. Keel's ship, the USS Horatio, was destroyed shortly afterwards, with Keel aboard. This incident, and evidence of a pattern in Starfleet's unusual orders found by Lieutenant Commander Data, led Picard to order the Enterprise to Earth to confront Starfleet Command directly.
Quinn boarded the Enterprise, and while Picard was on the surface Quinn attempted to implant Dr. Beverly Crusher with one of the parasites. However, Commander William Riker caught Quinn's attention first, and Quinn attempted to infect Riker instead. Riker attempted to fight him off, but was easily overpowered, as were Worf and Geordi La Forge. He was only subdued when Dr. Crusher shot him with a phaser set to kill.
Having subdued Admirals Savar and Aaron and Captain Scott, Picard and Riker tracked one of the parasites to a room where Dexter Remmick, inhabited by the parasite's mother creature, was waiting. Both Remmick and the mother creature were killed by heavy phaser fire at the hand of Captain Picard and Commander Riker, thereby also killing all other parasite infiltrators on Earth. Admiral Quinn, at least, made a full recovery.
- It remains unclear whether and to what extent the other admirals and Captain Scott recovered. However, given that Admiral Quinn suffered equivalent, if not greater, physical trauma than the others, it seems probable that all the afflicted officers survived.
However, the parasites' mother had sent a signal in to deep space which Data identified as a beacon, indicating that their return would only be a matter of time. (TNG: "Conspiracy")
- Despite this, the parasites were not seen again, though that might be simply because the signal hadn't reached its destination by the end of The Next Generation's run.
Biology
The parasites' natural appearance is that of light purple, crawling insects. A person inhabited by one of the parasites displays a noticeable spine-like protrusion from his or her neck. They are, apparently, incapable of inhabiting Soong-type androids such as Data.
The parasites appear to be highly intelligent, perhaps more intelligent than Humans. However, the parasites do not retain all of their host's memories, providing another means through which they can be exposed.
A Human inhabited by the parasites will display increased physical strength – such that the elderly Admiral Quinn was able to easily fight off three much younger men, including even Worf – and vitality. Even the resistance to phasers is increased. Not realizing that Quinn had been inhabited, Picard had commented that Quinn looked much healthier than the last time they had met.
The parasites are connected to their mother, a larger creature also capable of inhabiting a Human host. The death of this creature will also result in the deaths of all of her progeny. (TNG: "Conspiracy")
Apocrypha
- The neural parasites were (historically) first encountered on a comet near Trill, by then head of Trill Symbiosis Commission Audrid Dax, whose husband was a victim of a parasite, accompanied by Christopher Pike. However, the Trill authorities classified the knowledge and never released it to public; these events are depicted in the short story "Sins of the Mother" in the anthology The Lives of Dax.
- In the Pocket DS9 "relaunch" series of novels, Mission Gamma and the conclusion Unity had the neural parasites return in 2376, shortly after the end of the Dominion War. Shakaar Edon was one of those infiltrated and was assassinated by a Trill delegate to Bajor's entering of the Federation. It is revealed that they are similar to the Trill symbionts, as one of the previous Dax hosts' husbands was infected by one on a mission to an asteroid that was expected to pass Trill and showed a symbiont-like lifeform. The parasite fused with the symbiont and ultimately caused the death of both the host and the symbiont, a greater loss.
- In the novel Worlds of Star Trek: Deep Space Nine, Volume 2, it was revealed that the neural parasites were genetically created from Trill symbionts in an ancient Trill colony on Kurl.