Joshua Link was a member of the original Zodiac gathered by Taurus (Cornelius van Lunt).
The Gemini LMD was created by Scorpio to be a member of his Zodiac organization, which were activated early to deal with an attack by the Defenders. Gemini split into his two selves to fight the Defenders, but his two halves became confused about which side to support. Reason chose the Zodiac but emotion picked the Defenders, when the two sides merged, emotion won and Gemini decided to help the Defenders. Gemini helped the Hellcat, who was badly hurt by Leo, by trapping him in a water vent. When SHIELD came to clean up the LMDs, Gemini stayed around to make sure that the Hellcat was alright. Gemini turned himself in to SHIELD, though the Defenders put a good word in for him for his help during the battle. Nick Fury eventually released Gemini, not knowing what else to do with him.
Later, Gemini turned up in Los Angeles, with no money and an alcohol problem. He saved the LeClercs from being attacked by a would be hitman whom they hired to kill Morbius, but who was demanding more money. Morbius had killed their daughter in the time before he got his bloodlust under control. Jennifer Walters represented Morbius in court, and got him the lesser charge of involuntary manslaughter as it was deemed that he was unable to control his actions. The LeClercs, outraged at Morbius getting off on what they considered a technicality, then sought out the hitman. After Morbius saved them, they hired him to kill Morbius. Gemini accepted, but only planned on meeting Morbius to ascertain the extent of his guilt. After reviewing the evidence, Gemini decided that the court had made the right decision, but also realized the right in the parents rage over their dead daughter. As such, he decided to remain neutral in the matter. Morbius tried to commit suicide, wishing to keep Jennifer safe from the matter, but the LeClercs only saw this as an attempt at robbing them of their revenge. Morbius survived the fall, and Gemini mistakenly fought the She-Hulk in an attempt to keep Morbius from harm. Mr. Leclerc was then about to shoot Morbius, but suddenly realized that he had a choice as to whether or not to become a murderer, Morbius did not, so he threw his gun away. Gemini defeated the She-Hulk and returned Morbius to his lab so he took take the serum that counteracts his bloodlust.
Gemini later joined the rest of the Zodiac and a mentally unstable Quicksilver to attack the Avengers. Gemini, alongside Cancer and Quicksilver, attacked Avengers Mansion. Gemini fought against Captain America, but reverted to his good personality mid-way through the fight and surrendered.
Gemini was later released and was rebuilt (in a female form) through the use of the Zodiac Key and joined the rest of the Zodiac when they travelled to Dallas, Texas to confront the original Zodiac Cartel. They succeeded in killing all of the original members with the exception of Cornelius van Lunt and took their places in the criminal underworld. Next, they attacked a group of businessmen at a cattle auction in Wichita where they were opposed by the West Coast Avengers. Gemini and Libra both fought against Mockingbird, but fled when Sagittarius was destroyed by Hawkeye.
Much of Madison's past is unknown. He and his brother Lionel served in the US army during Vietnam War. Madison worked as a mechanic, Lionel as a medic. While Madison had always been uncomfortable with his powers, Lionel seemed to relish using his. Their unit was heavily damaged after a mission and Lionel seemed to go insane. He used his powers on the dead and wounded with horrific results. Madison had to use his powers to restrain his brother and had him committed. After returned home, he became a mechanic in the Canadian town of Harbordale, where post traumatic stress disorder caused his powers to go out of control and take over the entire town. The Canadian government sent Wolverine, who was working for Department H at the time, to investigate. He found and woke up Jeffries, freeing the town. After bringing him back to Department H, Madison was checked into a clinic where he met Roger Bochs.
Madison was apparently recruited by Guardian and was part of the Gamma Flight training group. He became romantically involved with Diamond Lil, also part of Gamma Flight. Madison's first major action was to dismantle Delphine Courtney when Omega Flight attacked Alpha Flight.
Madison worked on a new version of the Box robot with Roger Bochs. He was able to find or make a special type of living metal that allowed the operator to merge into the armor rather than control it via remote. Bochs and Jeffries then both officially joined Alpha Flight.
When Bochs started to go insane, Madison took possession of the Box robot. With his powers he could form weapons and devices to augment it as needed.
While James Hudson was presumed dead, Madison and Heather became close, and even became engaged. However, he continued to secretly see Lillian and eventually realized that he loved her and not Heather. He also helped James Hudson when he was captured by Roxxon.
Heather began looking into Madison's past and discovered his brother Lionel in a mental ward. Madison knew his brother was a danger and tried to stop her. Lionel was accidentally freed. Calling himself Scramble, Lionel escaped and set up a "New Life clinic" where he would work on others, claiming he could cure any ailment. Bochs was one of the ones who showed up, wanting new legs. The two then merged into Omega, wanting to use their combined power and skill. Although Persuasion was able to briefly separate the two, Scramble lobotomized Bochs and reformed Omega. Madison felt that his brother could never be rehabilitated, so he formed a large cannon and destroyed Omega.
He and Diamond Lil retired and married. Lillian attempted to keep him from using the Boxbot. Madison finally admitted he was becoming addicted to using it, as well as being an adventurer.
He still rejoined Alpha Flight after it was reinstated by Department H, although his wife asked him not to. However, she was able to convince him not to use Box unless it was absolutely necessary. On a mission with the team, Jeffries was knocked out battling the Zodiac. They brainwashed him into being Gemini and had him create a robot duplicate to control. Despite Puck finding and unmasking him, he seemed to still think Alpha Flight were his enemies.
Jeffries was then taken by Weapon X. He was manipulated to think that Director Colcord was his ally and not to question what the intended use of his projects were for. He was working on a new generation of Sentinels as well as using Box robots to keep the Neverland prisoners in line. He didn't even realize that his wife Diamond Lil was one of the detainees in the camp. With Neverland now abandoned, Madison and his prototypes accompanied Colcord.
He is currently living on Utopia and working with the X-Club to try and find a way to reverse the effects of M-Day.
Gemini was one of the members of the new Zodiac team, a group of ambitious people who wanted to conquer the World using special suits, which gives super-powers, supplied by Thanos, who wanted them to steal different powerful items and take them out from Earth in order to bring balance to the planet and the cosmos.
He was one of the Zodiac members who attacked the Helicarrier in order to retrieve an Ultimate Nullifier and he was left powerless when Iron Man used a sonic disruptor to shut down their special costumes and leave them powerless, Thanos appeared with the objetive to kill the Avengers for interfering in his plan. When Maria Hill activated the Helicarrier's self-destruct in an attempt to kill Thanos, the Zodiac's master left them to die in the explosion.
Avengers:United They Stand
Gemini was among the Zodiacs that appear in The Avengers: United They Stand with the male head voiced by Nigel Hamer and the female head voiced by Julie Lemieux. Gemini is depicted as a two-headed alien (one male head, one female head) with four arms.
When Tony Stark visited Japan to witness the opening of the new Arc Reactor power plant and the demonstration of the Dio armour, he spent time at Lab 23 where Dr. Tanaka worked as lead scientist. She assisted Stark in every situation in Japan until revealed to be a Zodiac sleeper agent Gemini.