Born as a regular flicky in Green Hill Zone, he was captured by Doctor Eggman and put into a Metal Sonic body, becoming just another face in the army, he, like the others was defeated by the original Sonic. After the fall of Eggman, he was left in a scrapyard for decades, until he was found by a kindly old owl that found him, the owl tried to free the flicky, finding that the flicky was far too badly damaged to survive outside of the armour that was essentially working as life-support for him. The owl fixed him up and gave the flicky full control of the body.
The Metal Sonic, not knowing anything about itself, stayed with the man, figuring things out. He came to call the man Grandpa. He came to love Grandpa and helped him with the heavy lifting around the house, staying by his side until the day Grandpa died of old age. After that, he went walking around the world. This is when he ran into Sonia and K'Tari, who had set out on her quest to find their brothers, respectively. Metal Sonic (Now going by the designation MS-2X4B) helped as a bodyguard as they searched.
They followed Manic to Station Square and foiled several of his plans there, before meeting up with Jack and G.U.N. to defeat him. During one raid, MS found the imprisoned Eggman and rescued him. Eggman gave MS access to the files on Metal Overlord and MS transformed to take on Manic's battle-fleet, but found himself unable to turn back afterwards. For a while, they transfered his Flicky into an old GEMERL body to continue their mission. After Manic absorbed the negative powers of the Chaos Emeralds to attain a dark Super-form, MS was transfered back into the Overlord body to fight him, but failed to defeat Manic. Jack, K'Tari, Sonia and MS then absorbed the positive powers of the Chaos Emeralds, transforming MS' body back to its Metal Sonic form and attaining super forms and defeated Manic. After the battle, Metal's body was badly damaged. The others harnessed the powers of the emerald and Metal was reborn into an organic body, an exact clone of Sonic.
Weapons:
Metal Sonic Suit (After he was transformed into an organic, Oglivie took his old Metal Sonic parts and, with the help of Eggman and Sonia, turned it into a battle-suit that increases his physical attributes to be on par with his old Metal Sonic body. This suit comes complete with built-in weapons and hardpoints that allow for different weapons to be equipped, depending on the situations. The built-in weapons include the following)
Machine Guns (Arms)
Missile Launchers (Shoulders)
Lasers (Helmet)
Flight-pack (Back and feet)
Black Shield (All over body shield, designed to protect against chaos-energy attacks, but protects against most attacks. However, whilst the blackshield is active, no other actions can be taken, offensive or otherwise.)
Natural Abilities:
Super Speed (Like his appearance would suggest, he is capable of running at mach-speeds)