During the corruption, Dark Sonic was outside of Sonic's body for a while because he just loved tormenting his 'friend' it was fun to him, Sonic didn't really care, he was just upset the dark sonic is here with him.

"Hey pathetic blue rat. HAHAHHAHAHA." Dark Sonic laughed as he held his stomach to urge his laugh in. Dark Sonic loved his life and tormenting Sonic in the process. He just loved it. It was like a daily job for him.