In Torchwood Season 3 aka Children Of Earth Day 2 we see that Jack "spawns" from his remains namely an arm, a shoulder and the remains of a head.(After being blown up by a bomb in his stomach) Now, if these remnants were kept separate would each part grow into a new Jack Harkness?
No. Captain Jack Harkness' ability to return from a death-like state is not a biological process similar to Wolverine's regenerative ability.
- Jack Harkness cannot die. Or perhaps we should redefine this as "he cannot stay dead". Any condition that renders him dead is invalidated and he returns to life. His condition is due to an improper use of the Temporal Vortex as applied by Rose Tyler.
Since his resurrection by the Bad Wolf entity, (TV: The Parting of the Ways) Jack could die and come back to life almost instantly, (TV: Everything Changes onwards) although on occasion his resurrection was delayed if he experienced enough trauma. This would cause his body to deteriorate from the slow healing, such as suffering the pallor of a corpse. (TV: End of Days, Children of Earth: Day One)
Harkness could also re-grow his whole body. After a bomb that was planted in his stomach exploded, he was able to fully regenerate from just an arm, a shoulder, and part of his head in a bit over twelve hours. His bones grew back first, followed by his internal organs, and lastly his skin, and it would appear that he retained all his memories and knowledge as well.
Jack chained up, after the effect of the explosion inside him. (TV: Children of Earth: Day Two)
- Wolverine is a mutant with a number of both natural and artificial improvements to his physiology. His primary mutant power is an accelerated healing process, typically referred to as his mutant healing factor, that regenerates damaged or destroyed tissues of his body far beyond the capabilities of an ordinary human. This power facilitated the artificial improvements he was subjected to under the Weapon X program (in later comics called the Weapon Plus program), in which his skeleton was reinforced with the virtually indestructible metal adamantium.
Our current experience says Jack Harkness returns to life, UNDAMAGED, indicating a possible return to a previous temporal state. But no matter his condition, he will resurrect and likely continue until he expires again. Judging from his nearly destroyed body event, I tend to go with him returning from a state of temporal grace, no matter how he dies.
Harkness would not create multiple versions of himself if he were completely blown apart but not disintegrated. Strangely enough, even if he were completely destroyed, he would somehow reappear, likely where he was destroyed. Having had as many deaths as he has experienced, if it were possible for there to have been multiple versions of via regeneration, he would have experienced it by now. See: Deaths
He has experienced multiple temporal versions of himself, however. See: Multiple Jacks
- Due to Jack's immortality and time travel, there were several occasions in which several Jacks existed on Earth at the same time. At the time of Jack's first encounter with the Ninth Doctor in World War II, there were three versions on Earth: the young mortal Jack who subsequently joined the Ninth Doctor and Rose; (TV: The Empty Child/The Doctor Dances) the immortal Jack working for Torchwood (location at this point in time unknown); (TV: Utopia, TV: Fragments) and a still older Jack being kept in cryogenic sleep at the Torchwood Three Hub in Cardiff. (TV: Exit Wounds) Later, when the Doctor, Rose, and Jack arrived in Cardiff prior to the Blaidd Drwg power station incident, they were only feet away from the Torchwood Three Hub where the older Jack was based and the cryogenically frozen Jack awaited resurrection. (TV: Boom Town, TV: Exit Wounds)