Sidney Potter era perseguitato dalla sfortuna finchè un esperimento medico, cui aveva aderito come volontario, non lo trasformò per errore in un berserk. Da quel momento la sua forza bruta gli diede tutto quello che non aveva ottenuto in precedenza. Potere e distruzione. La sua pelle è praticamente impenetrabile, anche se non è così intelligente da avere una strategia di attacco o di difesa …
Sidney Potter was a small-time thug whose string of bad luck got him locked away a third time. Potter knew his only chance to get any sort of leniency from the warden and the parole board was to volunteer for special medical experiments. Getting poked and prodded by a few eggheads in exchange for a few decades knocked off his sentence seemed like a good idea to Potter.
But Potter’s bad luck was just beginning. Upon discovering he was injected with the wrong experimental serum, Potter went berserk. When prison guards attempted to subdue him, he was thrown into a shelf full of chemicals, which entered his body through dozens of cuts caused by broken glass beakers. Fighting his way past the guards, Potter escaped into a rainy night, diving into a heavily polluted river—just as lightning struck. Scientists have since theorized radiation also figured prominently into Potter’s calamitous transformation, but none can agree exactly how.
A few days later, an enormous green-skinned, four-armed monster calling himself "Grond" went on a downtown rampage. The creature was captured, and tests conclusively proved the man-monster was once Sidney Potter, but no one could find a way to transform him back or hold Grond against his will for any amount of time.
In the years since Grond’s first appearance, the great brute has attacked sporadically, always proving to be an almost unstoppable destructive force and one of the world’s most dangerous superpowered threats. He’s gone on to cause billions upon billions of dollars of property damage and untold misery and left a swath of horrific destruction in his wake.
Grond is a creature of pure, unbridled rage, and enormous strength. His skin is nearly impenetrable, and he has the power and the brawn to literally take on armies and defeat them with ease. Grond is continually angry and possesses the intelligence of a young child, along with a child’s short attention span. This makes Grond impossible to reason with, though clever supervillains find him gullible and easy to manipulate. Grond is not intelligent or clear-headed enough to have any real grasp of tactics, opting instead to smash people and things that annoy him until they stop moving or something else distracts him.
Recently, Grond has returned to the Southwest Desert, to the radiated former nuclear testing grounds known as Uranium Flats. Years ago, this was the site of a previous Grond rampage that reduced an American Army base to dust and rubble. Grond says he has come to this remote area for the peace and quiet, but UNTIL scientists surmise he is seeking the plentiful radiation, which Grond’s strangely-altered body feeds on and processes to make the monster even stronger.
This time, UNTIL is ready. The base, now renamed "Project Greenskin," has been rebuilt, and UNTIL has recruited some of the world’s most powerful superheroes to help stop the creature before his next devastating rampage.