Silver Sonic did not originate from fanon, and more information can be found on their respective wiki(s). You may read more about it on the following wiki(s):

Silver Sonic
Silver Sonic
Full Name Silver Sonic (AKA Mecha Sonic)
Current Age N/A
Date of Birth November 21, 1992
Gender Male
Species Hedgebot
First Appearance Sonic the Hedgehog 2 (8-bit)
Latest Appearance Sonic CD 2
Mecha Sonic (often called 'Silver Sonic' after its Archie counterpart and to differentiate from the Sonic and Knuckles robot of the same name) is the first boss of the Death Egg Zone in Sonic 2 for the Sega Genesis. It is a robot modelled after Sonic the Hedgehog.