Heavy

Heavy is a clunky, silver robot created by Dr. Ivo Robotnik in 3235. Designed to create Bombs and act as a system's repair unit, both he and Bomb were one of the few robots created by the despot that had their own free will, which was what resulted in Heavy and Bomb abandoning Dr. Robotnik and joining the Chaotix. After helping the Chaotix to defeat Metal Sonic, Heavy and Bomb lived for some time on Angel Island until they relocated to Knothole where they joined the Royal Secret Service. However, after the Secret Service members were captured by Dr. Eggman, Heavy and Bomb were reprogrammed to act as sleeper agents which would begin to serve Eggman when he ordered them to. The original Heavy and Bomb were destroyed when they began attacking Knothole, but Dr. Eggman later produced newer versions, which were ultimately destroyed as well.

Creation and Joining the Chaotix
Heavy was created in 3235 along with his counterpart Bomb, both created to act as "mechanical mechanics, designed to seek out and repair damaged systems automatically". However, because Robotnik used Power Gems to power them, Heavy and Bomb developed consciousness and consciences. When the two discovered Robotnik's schemes to trap the Knothole Freedom Fighters in the Hall of Mirrors at Happyland Amusement Park, they left Robotnik and joined the Chaotix to help them stop Robotnik's plans. When Metal Sonic attacked the Chaotix, Heavy and Bomb aided in their efforts to destroy him. (KCX)

Members of the Secret Service
Some time after this, Heavy and Bomb sought out a place to fit in. Due to Heavy's ability to tap into Robotnik's database, he researched information regarding Geoffrey St. John and finally went to him in Knothole to join the Royal Secret Service. Realizing their potential, Geoffrey recruited them. (StH: #62)

Heavy and Bomb's first mission took them to Angel Island once again, this time to discover what had become of Queen Alicia during the Great War. The Secret Service successfully discovered Queen Alicia alive though in cryo-sleep and brought her back to Knothole. (KtE: #19, #20, #21)

Some time later, Heavy and Bomb accompanied the rest of the Secret Service to Robotropolis to locate and retrieve the missing Sword of Acorns from Dr. Eggman. During this mission, the entire team was captured by Shadowbots. During their time in captivity, Eggman had each prisoner brought out one at a time to seem like they were being interrogated. In reality, this was a ruse to get Heavy and Bomb out of site so he could have them reprogrammed as sleeper agents. Following this, Heavy and Bomb blew up the jail and enabled the Secret Service team to escape. (StH: #97)

Sleeper Agents
Following the rescue of the Robians from Robotropolis, Dr. Eggman activated Heavy and Bomb to begin attacking. Due to nanoprobes injected into the systems of Hershey Cat and Geoffrey St. John while in Robotropolis' jail, Bombs was able to incapacitate them by releasing a certain gas that activated the nanoprobes. Following this, Heavy produced hundreds of Bombs around Knothole, holding the Royal Family hostage. Although Heavy had the numerous Bombs programmed to blow up should he be destroyed, Sonic smashed through Heavy anyways. Before the Bombs could detonate, Rotor and Tails disabled them with an EMP generator. (StH: #102)

New Models
In 3238, months after Sonic's return to Mobius from outer space, Dr. Eggman produced new models of Heavy and Bomb to assassinate the singing star Mina Mongoose after Nack the Weasel failed to do so. However, these new versions were still quickly disposed of. (StH: #153, #154)

Background Information
The original versions of Heavy and Bomb featured their own unique designs. However, the rebuilt models were based directly off of their Knuckles Chaoix videogame appearance.