Professor Miles Warren created a virus at the High Evolutionary’s lab that was intended to turn the animal-like New Men fully human but which turned them into living corpses instead. Warren, as the insane Jackal, later modified this virus with his own genetic material and combined it with his own cell sample in a “clone casket”, hoping to create a creature that could poison everyone except clones. The Jackal, however, was apparently killed and never returned to his lab. The casket remained closed until Randy Vale, a former undergraduate student of Warren’s, opened it and Carrion emerged. A Warren clone/genetic virus hybrid with the Jackal’s desire to gain revenge upon Spider-Man for the death of Gwen Stacy and, as he soon discovered, the “death” of Warren himself. Under Carrion’s guidance using technology from Warren’s lab, Vale assumed the costumed role of Darter and became a willing partner in Carrion’s schemes in exchange for power. Possessing Warren’s knowledge of Spider-Man’s identity, Carrion offered his services to the Maggia but was rejected.
On his own, Carrion stalked Peter Parker and eventually faced Spider-Man at the Empire State University gym where he abandoned Darter and incapacitated the web-slinger with his mysterious red dust, taking him back to Warren’s lab and revealing his clone origins. He injected some of Spider-Man’s blood into a primitive amoebic clone ancestor of Peter Parker, creating a “Spider-Amoeba”; a large shifting organic mass with spider-powers that began crushing the chained-up wall-crawler. Darter burst in demanding that he should receive Spider-Man’s powers; Carrion turned on him and killed him with the red dust but not before a stray gunshot from Darter’s weapon freed Spider-Man. In the ensuing fight involving Carrion, Spider-Man, the amoeba and White Tiger (Hector Ayala), a fire broke out, distracting Carrion and allowing Spider-Man to throw the amoeba at him. Perhaps because of its clone casket origins, the amoeba negated Carrion’s genetic powers and consumed him, just before the fiery building collapsed upon them both.