Doctor Ivo Robotnik is the non-reuccuring main antagonist of SonicWhacker55. He does not live with Sonic, Robotnik in the videos goes to Sonic's house in disguise either to to rob him or confuse him. If not, he'll send a surprise to Sonic's house to abliverate the hedgehog at any cost at all.
He rarely appears in the videos, but he is obviously trying to rob and destroy Sonic. He knows where he lives, and as disguised hinself as "Santa" and tried to rob Sonic. His plans were foiled cause of Sonic, it is possible Robotnik is trying to get in Sonic's house.
Sonic - dr. eggman and sonic are enemies. Dr. eggman would try to take down sonic and friends but would always fail.