The Scorpion by Green-Mamba
MacDonald Gargan was a private investigator that Norman Osborn hired to keep tabs on Peter Parker and Spider-Man, to see if the two had any connection with one another. After one too many failed investigations, it is revealed that MacGargan is actually a convicted criminal with a police record of serial homicides, forcing Oscorp to let him go to save their reputation, and leading MacGargan in turn to forge an alliance with fellow Oscorp hater Adrian Toomes to begin purchasing alien weaponry and various armor application procedures to get their revenge on Spider-Man one way or another...