"The stain is heavily adapting constantly to challenges and threats, it can also cause the DX-1118 C to evolve, making it just as adaptive."
―An unnamed Gentek scientist.

The DX-1121 C Blacklight Virus was a mutated variant of the original DX-1118 C Blacklight Virus, the failed DX-1119 C Blacklight variant and the DX-1120 Blacklight Supersoldier formula, it was an incurable strain of the Virus and after being spilled its traits were adapted by the Innovators which made them just as incurable. It appears in Prototype: New Dawn.