WARNING: The following contains spoilers for Absolute Carnage: Weapon Plus #1, by Jed MacKay and Stefano Raffaele, on sale now.
Most people are familiar with the Weapon X program, but far fewer people are aware of Weapon V -- otherwise known as Project Venom. That isn't too surprising, as Weapon Plus is usually overshadowed by its most famous members. More people are familiar with the film-only Weapon XI in X-Men Origins: Wolverine than they are with the comics-only Weapon Plus groups -- especially not Weapon V, in which Vietnam War soldiers were bonded with alien symbiotes.
But one person who knows about the project is Carnage, who is out for the codices of all who ever bonded with a symbiote. This sets him on a crash-course with the surviving members of Weapon V, which he decimates in short, brutal succession.
The History of Weapon V
The Weapon V program wasn't started by the Weapon Plus government experiments to create a super soldier. Rather, it was spearheaded by S.H.I.E.L.D. Nick Fury himself oversaw the Sym-Soldier Program during the Vietnam War. Wounded soldiers would bond with alien symbiotes that had been extracted from the primordial mass of a symbiote known as Grendel.
Grendel belonged to Knull himself, the God of all Symbiotes, existing as his gargantuan symbiote dragon. The dragon would link any who merged with it to the symbiote God himself, which could have disastrous consequences if the wrong soul bonded with it -- like, say, Cletus Kasady.
The symbiote soldiers of the Sym-Soldier Program went on a rampage through Vietnam, performing Black-Ops missions for SHIELD. At first, this proved successful, but the symbiotes soon drove the soldiers insane, leading them to devour friend and foe alike due to the pure bloodlust of Grendel himself.
Fury wisely shut the project down, sending out Wolverine and former sym-soldier Rex Strickland to reclaim the soldiers. The project was soon deemed a success, with the sym-soldiers put on ice. However, Fury attempted to blow up his comrades to keep the whole mission a secret. Wolverine survived, while Strickland sadly did not. However, his symbiote, Tyrannosaurus, impersonated him, keeping him alive in theory.
The Legacy of Weapon V
This is when Weapon Plus took over the project, appropriating the remaining samples of Grendel and the frozen sym-soldiers. A revival of the Sym-Soldier Program would take place years later with Flash Thompson. However, they wisely kept Flash from bonding with the symbiote for more than 48 hours at a time, well aware that, should he remain bonded to Venom for too long, Knull's influence could drive Thompson into a murderous rage. Thompson wasn't the first soldier selected though. His predecessor, Cal Henrickson, went mental and had to be put down.
A second revival of the project, Project Liquid, was later spearheaded by the Weapon Plus program. Many of the Life Foundation's symbiotes were recruited to hunt down and kill Carnage. Mercury Team, however, soon found itself out-gunned by the murderous symbiote, who slaughtered them all.
Tyrannosaurus would later share the story of the Sym-Soldiers with Eddie Brock. Then, while fighting Grendel and Knull, Tyrannosaurus sacrificed himself in an attempt to kill Knull. It didn't work.
The whole while, however, Weapon V survived in secret, creating bio-weapons for their super-soldier program, appropriating data and information from all prior sources of symbiote-human bonding experiments, from the prior Sym-Soldier Program to the Life Foundation's efforts. All of it in order to create weapons.
Any plans they might have had, however, were soon dashed by Carnage. Carnage, now fully blended with Knull and his cosmic influence, has gone out to collect the codices of every symbiote around. Before the events of Absolute Carnage began to unfold, however, the monstrous symbiote went after another team of sym-soldiers: Project Mars.
Project Mars re-assembled to combat Carnage after the red symbiote tracked down and stripped the spine from various participants of the Weapon V program. They understood Carnage had fallen under Grendel's influence after blending with Grendel's essence.
The Mars Team consisted of multiple sym-soldiers, as well as Clayton Cortez -- or Weapon H, the Weapon Plus's attempt to blend the Hulk's strength and Wolverine's regenerative abilities and claws. Any attempt to kill Carnage before he could unleash his nightmare across the Marvel Universe, however, proved futile. Even with all his strength, Cortez could barely stop Carnage. While Cortez managed to escape, the Mars Task Force is otherwise eradicated.
Things became even more complicated when it turned out that one of the scientists involved with Weapon V, Andrew Breen, betrayed them all. He understood Carnage's role as Knull's avatar on Earth. Rather than fear that, he longed for Carnage to succeed at his tasks, having become a worshiper of Knull through his involvement with the symbiotes.
Weapon Plus, however, seems unconcerned by all of this, moving on to further plans that might include their symbiote bio-weapons. Still, they keep an eye on the Carnage situation, hoping to learn something valuable from the violence.