Harkness is known for his love of tight asses and once buggered Prince Charles on a dare. Rumor has it that he becomes a large fucking head with testicle dreadlocks.
He is known to be armed with an arse gun at all times.
Despite having a long and storied run as the MOST IMPORTANT COMPANION SINCE THE PREVIOUS MOST IMPORTANT COMPANION during the Russell T. Jimmies era, Captain Jack never showed up during Steven Moffat's reign. He was apparently supposed to return for A Good Man Goes to War, where he would have been decapitated, which actually would have been kind of clever, but Barrowman didn't return because he's based and hates Moffat's writing.
Jack is beautiful and has magnificent teeth.
He fucked a 4channer in a hotel during a convention. Never forget.