Kieran Frost was Head of Security for Torchwood One. While popular with others, Kieran remained quite secretive about his personal life.
In 2005, Kieran and his team tested newcomer Rachel Allan on her observational skills. Later that year, Rachel successfully set him up with his personal assistant, Dean. Rachel convinced him to come out to his family. She attempted to get him to volunteer to test the Royal Hope transmat but Dean did instead and was killed. This still achieved her goal of weakening the Security Department. (AUDIO: New Girl)
Still mourning for the loss of his partner and refusing leave, Kieran was given the task of killing Yvonne Hartman by Rachel Allan, the new director of Torchwood. Not long after catching Hartman, he was knocked unconscious by Soren, allowing Hartman to flee. (AUDIO: Through the Ruins)