After surviving an explosion in the city of Nightshade, Packrat and his gang take Spider-man 2099 to there hideout in order to make him to activate the robot, which he does. Once activated Flipside becomes a combination of Venom and the original Spider-Man, since Spider-Man 2099 does not exist in his outdated records. Flipside then jumps into Spider-man 2099's arms and says they will be best friends or he'll kill him. When Spider-Man 2099 rejects his friendship, Flipside becomes enraged and attacks Spider-man 2099. Flipside has battled Spider-Man 2099 many times but never defeated him and after yet another defeat Flipside ran away and has not been seen since.
After he turned against spider man he rebuilt his costume to be bat themed. He has retractable razor sharp wings and countless other weapons and gadgets. He can even fire pulse beams.
Flipside appeared in the Spider-man video game "Spider-Man: Shattered Dimensions" as an alternate costume and mentioned in a joke saying " Whoa this guy makes Flipside seem sane."
Flipside also appears as an alternate costume in "Spider-Man: Edge of Time".