Abaddon: Angel of the Bottomless Pit or Realm of the Dead?
In Torchwood's first series' finale episode, "End of Days", the Hub's team is at odds over Owen Harper's use of the Rift Manipulator and mutiny is in the air. Death and destruction are leaking from the spatio-temporal cracks which start at the Cardiff Rift and time is running out in a literal fashion.
Mutiny. Death. Destruction. Cue Abaddon, the angel of the bottomless pit.
It's a passion play of sorts.
The story of Abaddon, in Earth's history, is that of an angel-prince of hell or maybe just the land of the dead. He's found in Abrahamic faiths as a place and an entity, both a minister of death and a destroyer of the satanic sort.
For Cardiff, he looked like a Balrog. No, really. He did.
In the oldest texts, he is associated with Sheol, a realm of the dead. The Hebrew word 'abad' translates as 'he died' and the word in its whole form indicates ruin and destruction. As it evolved in religious texts and was included in Catholic and Protestant doctrine, Abaddon came to represent both a place of destruction and the angel of the bottomless pit. His place in the story of Armaggeddon is assured with a plague of locusts and trumpets.
Abaddon is seen as being parallel to Sheol and Death, the grave itself. It represents, in its source words, the more negative aspects of what occurs after death.
The dual nature of the word itself makes for an interesting story. Jack Harkness, whose secrets in the face of the teams individualized suffering, is betrayed through a mutiny and his biggest secret is destroyed. He dies in front of them at their hands, an event that has its roots and foreshadowing in previous episodes, in moments when each member of the team has shown extreme dissatisfaction with the mask Jack wears.
It's with Rhys' death and Gwen's reaction that we see the truly desperate man living under the sly good humor and fierce loyalty to a cause; this is the last straw for the team where Jack's hard-nosed sense of secrecy is concerned. To a member, they agree with Owen Harper's condemnation. Jack's most alien feature is revealed just at the moment when the seal is broken and the imprisoned Abaddon is released; he gets up off the floor and goes out to fight with the only weapon he has--his apparent immortality.
With his self-sacrifice in the face of unbeatable odds, Captain Harkness shows himself to be the hero once more. It was this same sort of action that caused his unusual lifespan in the first place. He throws himself to Abaddon just as he threw himself to the Daleks in the Doctor Who episode, The Parting of the Ways", proving he's worthy of what the Doctor represents.
As a trapped alien threat, Abaddon's place in the larger story arc of Doctor Who and its connections to Torchwood has been seen before. The Doctor encountered a similar demonic entity on a distant world in the future where Torchwood was drilling for access to a mysterious power source that was holding a planet in tenuous orbit at the gravity well of an overshadowing black hole. In the Doctor Who episodes "The Impossible Planet" and "The Satan Pit", the imprisoned Beast is known by many names, among them Abaddon. Its appearance and behavior marks the two instances of imprisoned aliens as being from the same species and perhaps related in some fashion.
Within this episode, we also see Abaddon as a concept with the destruction of Jack's secret. Jack no longer can hide the truth about his undying state of existence--he is killed and returns to life to go on doing what he does. He saves the world using the double-edged sword that is his near-immortality.