Spider-Man's black costume was initially a refreshing change of pace from his iconic red and blue suit. Peter Parker was fascinated by this unique new outfit, appreciating its many benefits. When Spider-Man discovered the truth about the black costume, however, his opinion drastically changed. The black costume first appeared in 1984's Amazing Spider-Man #252, by Tom DeFalco, Roger Stern and Ron Frenz. Spider-Man was revealed to have discovered this strange new costume on Battleworld, during Secret Wars #8, by Jim Shooter and Mike Zeck. When the web-slinger first came upon the black suit, he saw it as little more than an exciting new costume that came from an alien costume repair machine.
While its appearance may have been different than his original costume, Peter thought the black suit may have been inspired by the costume of Julia Carpenter, the second Spider-Woman. Of course, there were some tell-tale signs that the black costume was more than just ordinary clothing.
The black suit produced its own webbing and responded to Peter's thoughts by changing its appearance. This new costume also came on and off as Spider-Man commanded and repaired itself automatically. The biggest concern, however, was that, in the middle of the night, the black costume would slink across Peter's room and approach him while Spider-Man was sleeping. During Amazing Spider-Man #258, by Tom DeFalco and Ron Frenz, it was revealed that the costume was attaching itself to the sleeping Spider-Man and taking his body out on nightly patrols across the city. This explained why Peter felt physically exhausted during the daytime. While he was sleeping, Peter dreamed that he was back in his high school clothes, being chased by the black suit.
Spider-Man's classic red and blue costume was also fighting the black suit for Peter, tearing him apart. With this nightmare, Peter decided to uncover the truth about the black suit once and for all. Spider-Man took the costume to Reed Richards of the Fantastic Four for analysis. After some careful examination and testing, Mister Fantastic concluded that the suit was an alien symbiote that would eventually permanently bond to its host, Spider-Man.
This revelation was a major turning point for Peter's perception of the black costume. No longer was the suit a unique new outfit. Instead, the alien symbiote was a threat that needed to be eliminated. Immediately, Peter tried to remove the suit, but the symbiote only attached itself even more to the wall-crawler. Fortunately, Reed figured out the symbiote's weakness to sonics, using a sonic blaster to remove the symbiote, while the Human Torch used his flames to contain the suit.
Although the symbiote was contained in the Baxter Building, it escaped captivity in Peter Parker, the Spectacular Spider-Man #98, by Al Milgrom and Herb Trimpe. The costume tried to reattach itself to Peter in Web of Spider-Man #1, by Louise Simonson and Greg LaRoque. Spider-Man was able to remove the symbiote by using church bells to weaken it, nearly dying in the process. Resigned to this rejection, the symbiote saved Peter from certain death, before leaving him alone. Even though Spider-Man wouldn't wear the alien costume anymore, the aesthetic of the black costume lived on. In Peter Parker, the Spectacular Spider-Man #99, by Al Milgrom and Herb Trimpe, the Black Cat made Peter a cloth version of his black costume. Reluctant at first, Peter eventually made the black suit his primary costume for a while.
Of course, when Peter faced Venom in Amazing Spider-Man #300, by David Michelinie and Todd McFarlane, he was forced to abandon the black suit, as it was too closely tied to his horrific nemesis. Still, both the black suit and the alien symbiote have endured in the Spider-Man mythos. Some of Peter's darkest moments have seen him don the cloth version of the black suit, indicating the gravity of a particular situation. Additionally, the alien costume bonded with Eddie Brock to become Venom, which later led to the birth of Carnage and a whole host of symbiotes. Revealing the black suit as an alien symbiote eventually led to the discovery of the symbiote god, Knull, who has played an important role in recent years. Once Spider-Man's black suit was revealed as a living organism, the door was opened for a whole mythos surrounding alien symbiotes.