I never saw any chemistry between Brian and Michael. From the moment Brian and Justin kissed I had Brian and Justin blinders on and couldn't see anyone else. Seriously though, while it was obvious Brian loved Michael as a friend a never felt any legimate sexual attraction on his part. Certainly therre are plenty of times we saw longing on Michael's part, but nothing I would call chemistry between them.
There are hords of Brian/Michael shippers who would disagree with me but what do they know. lol