
A Changeling being experimented upon for Project Proteus
Project Proteus was a secret program conducted by Section 31 on Daystrom Station during the Dominion War in the mid-2370s.
Goal[]
The project's goal was to engineer an evolution in the Changelings that would allow them to completely replicate the biology of any species and fool blood screenings and other methods of detection, thereby acting as "perfect spies" for the Federation.
It involved conducting torturous experiments on ten Founder prisoners of war. The work eventually yielded a chemical formula, which used thelomium-847 as a stabilizing agent, that enabled a Changeling to fully mimic the anatomy, physiology, and cytology of any species.
Flaws in the experiment[]
The enhancements, while potent, came at the cost of constant pain, a shortened life span, and even added weaknesses. As, due to its experimental, prototypical nature, the serum possibly did its job too well: in so perfectly mimicking solids, it seemed to give them some of the same vulnerabilities as solids, which a normal, unaltered Changeling would not be affected by. It seemed that while the experiments done to the Changelings did make them exponentially better infiltrators, it also seemed to make them much more vulnerable to the normal methods of killing solid beings.
Vadic was able to form a sharpened tentacle to kill the scientist who had experimented on her, however she was in an amorphous state at the time and not in active combat. (PIC: "Dominion", "Surrender")
Furthermore, defensively speaking, they seemed to show other deficiencies as well. For example, bladed weapons would never have threatened a normal Changeling, but the altered Changelings were seemingly temporarily incapacitated by them because their mimicry included vital organs and they seem to experience pain when impaled. Though it could not kill them, and they could regenerate quickly, it left them vulnerable to an immediate, successive, vaporization by a phaser.
Additionally, while normal Changelings would survive exposure to the vacuum of space, (DS9: "Chimera") the evolved breed of Changelings were killed by it, as their empowered ability to impersonate others may have weakened the Changelings' ability to maintain a considerable amount of their ductility and flexibility; thus, once exposed to the vacuum of space, unlike other Changelings in the past, it proved fatal for the new, evolved, breed of Changelings as they froze completely solid, and shattered upon collision with another body in space, such as a ship. (PIC: "Surrender")
Further flaws were shown in the biological modifications. The modified Changelings, or least younger and more inexperienced Changelings similar to Odo, may have still needed to return to their natural form after some time, or else their disguise would wobble from exhaustion. Also, contrary to regular Changelings, Betazoids could feel evolved Changelings' emotions and sense that something differed when approached by an impostor. (PIC: "Surrender")
And, by using thelomium-847 as a stabilizing agent in the formula they created to enhance a Changeling's metamorphic abilities, trace amounts of the chemical were present in all of the Changelings who were given these enhancements. This could be taken advantage of to track the modified Changelings remotely. Normal Changelings did not suffer from these flaws. (PIC: "Dominion") Dr. Beverly Crusher was later able to figure out a way to detect these evolved Changelings using Starfleet's transporter system. (PIC: "The Last Generation")
The disastrous outcome[]
In sum, the project, while it was successful in its efforts to create a subspecies which could pass all the tests, failed in many ways. For one, as the enhancements were experimental and prototypical, the project failed to correct the flaws in the biological modifications, nor did the scientist overseeing the project succeed in insuring loyalty in the recipients of the treatments. Consequently, the project went awry when one of the modified Changelings, who would become known as Vadic, killed the project's lead scientist and escaped with the other nine prisoners. Later on, Vadic found they were able to pass on their experimental enhancements to other Changelings who linked with them after forming their own splinter faction of the Great Link to pursue vengeance against their former tormentors. (PIC: "Dominion")