The character's major storylines have centered on his relationship with his family. He reunited with Tricia and discovered that she had been raped by his father, meaning Chrissie was actually his biological half-sister. Although the couple were able to put the past behind them and remarry, Tricia was killed in a road traffic accident in 2006. Mark struggled to cope in her absence, succumbing to a cocaine addiction in 2007. The character was later promoted to the hospital's chief executive officer. Powell left the serial in 2010 and Mark departed in the series thirteen episode "Don't Go Changing", broadcast on 25 February 2011. The character was well-received by the audience, although his cocaine storyline was criticised for its surrealism in the media.