Who is Sonic's long lost brother?

Could you elaborate on the concept of Sonic's long lost brother? Is this a reference to a character from the Sonic the Hedgehog franchise, or is it a hypothetical scenario? If it's a character from the franchise, can you provide some background information on who this brother might be, and what role he might have played in the story? Additionally, are there any specific games, comics, or other media where this character is featured prominently?