S03E07: 'Fresh Blood'

Sam and Dean capture a female vampire named Lucy who claims to have no knowledge of how she became a vampire.

The guys discover Dixon, a male vampire, is giving out human blood to unsuspecting females in bars, offering it up as the "latest drug" and turning them all into vampires.

Meanwhile, Gordon escapes from jail and goes after Sam. However, Dixon intercepts Gordon and turns him into a vampire, which makes Gordon more powerful than before and a much bigger threat to Sam.