Meta-Crisis Tenth Doctor

The Meta-Crisis Doctor is a supporting character in Series 4 of the revived series of Doctor Who. He was a hybrid of Time Lord and human and a human incarnation of the Doctor. He possessed one heart, aged as humans did and possessed no regenerative ability. He was created by an instantaneous biological meta crisis and was the final result of the Tenth Doctor's aborted regeneration.

However, this Doctor was born in a separate body than the original Doctor, existing as a separate person with DNA sampled from Donna Noble. These genetic alterations caused him to develop a unique, less merciful personality that deviated from the moral code that his counterpart followed. The new Doctor needed someone to look after him and quell the fire in his veins, and shared the same romantic feelings toward his companion Rose Tyler that the original Doctor could not accept as a slow-aging Time Lord. Thus, the Tenth Doctor made sure this version of himself would enjoy his life with Rose Tyler in Pete's World, fulfilling the need to make him a better person, and so his duplicate could give Rose the romantic life that she desired in his stead.

Like the Tenth and Fourteenth Doctors, he is portrayed by David Tennant.

Biography

The Doctor's Hand

On Christmas 2006 in The Christmas Invasion, the newly-regenerated Tenth Doctor lost his hand in a sword fight against the Sycorax leader. Captain Jack Harkness later retrieved the hand and returned it to the Doctor in a jar in Utopia, which was used by the Master to augment his laser screwdriver with an ability to age the Doctor, while preventing regeneration. After psychic energy from humanity restored the Doctor's vitality and allowed him to defeat the Master, he took his lost appendage to keep by the TARDIS console. The Doctor's hand remained in the TARDIS until the Doctor was grazed by the blast from a Dalek gunstick, triggering his regeneration. After healing the damage to his body with the regeneration energy, in Journey's End, the Doctor channeled the excess energy into his hand, allowing him to heal without changing his appearance and personality. Even though the regeneration was aborted before it could be completed, the fact that the Doctor siphoned off the energy that would've changed his appearance after healing his injuries, he used up the same amount of regenerative energy as a full regeneration. This, as the Eleventh Doctor later told Clara Oswald, meant that his previous incarnation used up one regenerations due to "vanity issues."

"Birth"

Shortly after this aborted regeneration, the Daleks attempted to destroy the Doctor's TARDIS. Still inside the TARDIS during this apparent destruction, Donna Noble touched the energised hand's container. The regenerative energies present within the hand combined with Donna's human DNA, causing an instantaneous biological Meta Crisis. The force of the reaction shattered the container, allowing the energy to regenerate the entire missing body of the Doctor. In this process, the "Meta-Crisis Tenth Doctor" was created. He immediately dematerialised the TARDIS, saving it and Donna.

Genocide and Exile in Pete's World

After putting on a blue suit, the Doctor and Donna left the TARDIS and tried to attack Davros and the Daleks with his new weapon. Both were electrocuted by Davros. After the now-part-Time Lord Donna defeated the Daleks, she, the Meta-Crisis Doctor and the original Doctor teamed up to return all but one of the planets to their rightful places. The Meta-Crisis Doctor was then prompted by Dalek Caan to fulfil a prophecy by destroying the Daleks. He chose to do so and ignored pleas from both Davros and Donna. He proceeded to overload the Dalekanium power feeds, causing virtually the entire New Dalek Empire to explode, from individual Daleks to the Crucible itself. As the Meta-Crisis Doctor was born from the Doctor, Davros refused his offer of rescue, instead condemning him as "the Destroyer of Worlds" (somewhat ironic considering his now defunct Reality Bomb).

Feeling his new, part-human counterpart was too dangerous to be left to his own devices, the Doctor entrusted him to Rose Tyler, taking the two of them back to Bad Wolf Bay in Pete's World. The Doctor told Rose that his part-human self needed her, that he was angry and vengeful as he himself had been when he first met Rose. He told her she had made him better, and now she had to do the same for his other, part-human self. Rose objected to this at first, insisting that the new Doctor was not really him, despite the Doctor's assurance that they were the same man and the part-human Doctor offering to spend the rest of his life with her. Rose asked both Doctors what the last thing they had said to her was when they were originally standing on Bad Wolf Bay. The Doctor was unable to give her a direct answer: "Does it need saying?" She posed the same question to the part-human Doctor, who whispered it in her ear.

Seemingly overcome with the revelation of his answer, Rose grabbed the lapels of the part-human Doctor and pulled him into a kiss, which he reciprocated. The Doctor looked on sadly yet stoically for a moment before returning with Donna to the TARDIS and leaving the parallel world. As the doors of the TARDIS slam shut, Rose and the part-human Doctor break from their kiss and hold hands as they watch TARDIS dematerialise.

Settling down with Rose

While he would continue to be addressed as "the Doctor" by others, some accounts say that the Doctor decided that he would personally go by a different name, by which Rose would also refer to him. By one account, he chose the name "Corin", a name that Rose considered to be "solid and true". Another account posited that he chose his old alias of "John Smith". Both accounts agreed they eventually had a child, which the comic Empire of the Wolf depicted as a girl they named Mia.

Working with UNIT

The Doctor, Jackie Tyler, Peter Tyler, and Rose later joined the newly established UNIT, created when the Preachers were combined with Torchwood by President Harriet Jones. The Doctor was given a lab at the top of UNIT's base at Big Ben, where he attempted to build a TARDIS. At one point Brigadier Krista Lateef attempted to force him to use his time machine to change her personal history, but the Doctor and Jackie were able to affirm that the machine wasn't ready yet, even if the rules of time travel didn't forbid such an act. The Doctor subsequently reported Krista's actions, much to Jackie's anger as she'd agreed to forgive Krista for the deception.

In an attempt to get the Doctor and Jackie to talk to each other after their disagreement, Rose and Pete tricked the Doctor into getting on a zeppelin with Jackie headed for Hull. During the flight, an alternate Jackie from a different universe appeared and threatened to shoot Jackie and take her place in Pete's World. The Doctor shot the zeppelin's flight controls, forcing the alternate Jackie to go back to her own universe to save her own life. The Doctor and Jackie then leapt from the zeppelin and into the water moments before the zeppelin crashed into the Humber Bridge.

Personality

As a result of growing partially from Donna's DNA, the new Doctor inherited some of Donna's mannerisms, although her more rambunctious traits eventually faded, leaving only human inclinations that he would have lacked as pure Time Lord, such as willingness to properly reciprocate Rose's love. He claimed he had the same memories, thoughts and feelings of the original Doctor up to the point of his aborted regeneration, making them essentially the same man with physiological differences. However, the original Doctor was quick to point out that his new double was "born in battle, full of blood, anger and revenge". In this way, the Tenth Doctor described his duplicate as representing the way he had been during his former incarnation before meeting Rose. This motivated him to commit attempted genocide against the Daleks, an act the original Doctor condemned after the events of the Last Great Time War.