This is one of the worst storylines I have ever come up with in my entire life. I laugh at it now, because I probably wasn't thinking at the time I posted it.
Dr. Robotnik was working in his lab when Metal Sonic crept up behind him. Dr. Robotnik turned around and said "Metal Sonic? Get back in your cage!" And he said, "No way, Eggman!" and hopped out of the window. Dr. Robotnik was stunned, as the only one who called him Eggman was Sonic. He had to get him back!