If a pilot picks up a rotation that begins and ends at his/her home base, any deadheading to or from that base is still a part of the work rotation even if it's "heading home". If a pilot is based in YYZ but lives in YUL then it is commuting to go YYZ-YUL, and generally the pilot has to fly standby or positive space without any special benefit. Sometimes commuters get priority and could bump passengers if not bumping means a downstream flight is impacted.