"Think of this, Doctor. To once again touch the skin of your beloved. To hold your beautiful child in your arms again. To have love once again. Oh yes, Doctor, I would kill for that!" -- Penthos
Dr. Gordon Pento was a scientist who was among many colonists, including some soldiers who migrated from Earth and terraformed the small asteroid, Chapman 17J. However, after attempting to defy the amourous soldiers who requested his wife and seven-year old daughter, he was maimed in an explosion. Rebuilt with cybernetics but losing his connection with other lifeforms - he became Penthos, a tragically hateful and scorned individual who desires to be human again and will do anything to acheive it.
Gordon was thought to have been a very empathic individual who cared deeply for others and wanted to know more about the mechanics of life and its origins. THis is what made him want to become a scientist.
Life as a scientist
As a scientist, Pento knew more about the functions of telomeres (which are thought to prevent ageing) and cellular regeneration than any other human. This made him a world-renowned academic and became a scientist for the government. They then asked him to assist in their new 'Exodus Program'.
The 'Exodus Program'
Pento found this exciting, as the Exodus Program meant that terraforming and colonising an asteroid successfully could mean humanity's growing population could stretch out to new planets that could become hospitable for them very soon if the program succeeds.
He took his wife and daughter and they all became colonists along with governemt officials, several soldiers, many scientists and many more civilians who volunteered.
Some soldiers that were there to keep authority and order within the colony became isolated and growing more insane while on the asteroid. They seeked out Grace as someone they could easily have their way with. Not only that, the vile soldiers also found potential in Claire as well.
Attempting to fight them off, the soldiers kicked Pento into an electric generator which was about to go critical. One solider, Lieutenant Clark shot Grace and Claire right in front of Pento and fled before the generator exploded and apparently killed him.
The incident was thought to have been an accident and Grace and Claire's bodies were to burnt to show any signs of bullet wounds.
The scientists located the mutilated and maimed remains of a still-living Pento. Quickly, they reassembled him using robotic attachments and replacements, until he became a cyborg creature. Flesh and steel was welded together to make Penthos the monster he is now.
Destruction of the colony
Lt. Clark ordered one of the privates to shut down Pento's life support system at nightfall. When the soldier got to the comatose Pento, he saw that he was not only finished but awake. The crazed scientist mutilated the soldier and reassembled him into a cruder and less-efficient kind of cyborg than he was. He left the lobotomised cyborg private to slowly die of brain death as the cybernetics slowly lost power.
He then went on a rampage in the medical centre, killing the staff, the scientists that revived him and even the patients. All had become just like the soldier that Pento first killed. He then saw what he had to call a face from now on and it brough him over the edge with rage and pain. He proclaimed that Gordon Pento was dead and 'Penthos' was who he was now.
He then killed the other colonists and left the remaining soliders last. He killed three of the eight that were still alive. They however, hid and Penthos searched and waited for them. He created robot servants to carry on his searching while he searched for a way to create a human body to transplant his brain from his cyborg shell. He also planned to resurrect Grace and Claire with his research in moleculear regeneration. However, he would have to regain his face if he is to have a chance to be with his wife again.
Clash with the Doctor
The Doctor and Amy Pond land on a barren wasteland that Chapman 17J has become. They locate the surving soldiers who have been hiding in different parts of the asteroid for months to keep out of Penthos' gaze. Their arrival is spotted by one of Penthos' robots and they are then captured. Penthos sees the Doctor's genius and asks him to help him regain a new body to let him be with his family again. The Doctor sadly declines as 'if I let you all return as you were, you would see what you have done and it would kill you inside'. Penthos is enraged and heartbroken when he realises that his revenge has killed any chance of Grace loving him again or being able to hold his daughter again.
However, he then had an idea that he could reprogram their brains into seeing past that. The Doctor asks if that is what he wants with his family - obedient puppets. Penthos laments and decides that there is no point to any life and proceeds to kill everyone on the asteroid. He succeeds in murdering all the soldiers except Clark who he captures again and proceeds to torture him more than any other of his victims. The Doctor and Amy are too late to save him as they see Clark has become a puppet, with his head severed and placed on a small robot body, like a warped parody of a young child. The insane Penthos names it 'Son' and the deranged and vacant Clark head responds darkly by affectionately calling Penthos, 'Daddy'. Penthos then sets his eyes on 'making more children', and advances on the Doctor and Amy.
They run to the cemetery and show Penthos the last remnant of his humanity: the graves of Grace and Claire. Penthos drops to his knees and apologises for what he has done and decides that in order to be with them again - he must die too. He then tells them to leave as he removes his chasis and takes out a glowing orb which is his 'heart' - actually a perpetually operating power core. His robots gather and bury their fallen master beside his wife. They then place the power core on a steel plinth inside a magnetic feild as a sort of gravestone, which reads 'Gordon Pento'.
After the TARDIS leaves, Penthos' voice is heard from the power core, singing 'Rock-a Bye Baby', and is joined by the voice of a young girl - stating Penthos still, in a way, is alive.
After his near-death ordeal, Penthos has lost all hope for life or the goodness in any sapient lifeform. He sees anything innocent as destined for destruction and anything evil worthy of it. He is obsessed with regaining humanity so that he could regain his form and use his expertise in molecular regeneration to resurrect his wife and daughter. However, though he may have a way of resurrecting the dead, he has no way of being able to reconstruct the human tissue he lost as the successful treatment would kill him as he would be out of his life-supporting robotic form for too long. He despises authority figures, especially military. Anger seems to be the only strong emotion he can feel apart from sorrow.
Penthos is forced to wear a metallic neck brace that covers everything from his chest up to his mouth and the top of his head. His mouth looks similar to the mouth of Doctor Doom's mask from the Fantastic Four. He speaks in a heavily electornic (almost like Stephen Hawking), refined English voice, but displays no positive emotion in his speech whatsoever - everything he says has a sorrowful and lamenting tone to it.
His hands have been replaced with robotic hands that are covered by silver leather gloves. He also wears a long robe which hides the hideous mixture of robot and human parts and his legs have been replaced with a 'hover-engine', quite similar to the bottom of a Dalek. This makes him glide instead of walk. His face is still human but his eyes are covered by black goggles as the explosion near destroyed them and now has to make due with robotic replacements. His skin has gone grey and pale due to the heavy loss of blood.