John Smith (Tenth Doctor)

John Smith was a human identity the Tenth Doctor created for himself when he used a Chameleon Arch to disguise himself from the Family of Blood. The name "John Smith" was actually one of the Doctor's many aliases.

Biography
According to Smith's memories, he was born circa 1880 to Sydney Smith, a watchmaker, and Verity Smith, a nurse. He was raised in the Radford Parade district of Nottingham, on Broadmarsh Street. The Smith family retained a maid, Martha Jones, who continued to serve John after the deaths of his parents.

John received an excellent classical education (probably in a school similar to the one he taught at in 1913, as he seemed familiar with the customs) and became a schoolteacher himself. A talented artist, he studied art in "Gallifrey ", presumably in Ireland. John took a new job in the autumn of 1913: history teacher at the Farringham School for Boys, in Farringham, England. Not long after arriving, he began having strange and vivid dreams: that his maid Martha was in fact a medical student from 2007, and that he himself was an adventurer in time and space known only as the Doctor. Fascinated by the intensity and strangeness of his dreams, John began to keep A Journal of Impossible Things, in which he recorded the adventures as the alien Doctor, insofar as he could remember them. He illustrated with rough sketches.

By November of 1913, John had begun telling others about his dreams: first his maid Martha; then the school's nurse, Matron Joan Redfern with whom he was surprised to find himself falling in love. Though in his mid-30s, John had never before been in a romantic relationship.

His courtship of Joan, however, was interrupted by an increasingly bizarre series of events centred around himself, and it became increasingly evident to John that, deny it though he would, he was not entirely human. His dreaming-self, the Doctor, was the true self; he was, as he put it, "just a story".

Eventually to stop the Family of Blood, Smith decided that he must become the Doctor again, even if it meant that he would "die". At one point Smith envisioned a possible future in which he and Joan marry, have children and grandchildren, grow old, and ultimately pass away from old age, secure in the knowledge that everyone that he loved was safe. He opened the fob watch off-screen and reverted into the Doctor, who pretended to still be him, allowing him to defeat the Family of Blood. Later, Joan rejected the Doctor's offer for her to come with him, stating that John Smith was dead and that the Doctor just looked like him.(DW: Human Nature/The Family of Blood)

In the future, Joan's great-granddaughter Verity Newman published his "A Journal of Impossible Things" as a book and revealed to the Doctor that after John turned back into the Doctor, Joan did have a family and live a happy life. (DW: The End of Time)

Personality
Smith's humanity made him far more emotional than the Doctor, whose actions often seemed cold or ruthless - the contrast between Smith before his essential 'death' and the return of the Tenth Doctor who then proceeded to essentially torture the Family of Blood should illustrate this. He was aghast at Martha's revelation that the Doctor was indifferent towards or perhaps incapable of love; terrified of Tim Latimer's description of the Doctor's alienness; and, finally, shattered that becoming the Doctor meant that his own life as a separate entity would end. After John 'passed away', Joan Redfern held the Doctor in some degree of contempt for choosing to come to England in 1913, lamenting that 'if he had never chosen this place on a whim...would anyone here have died?' John was, she told the Doctor, braver than him for choosing to die to protect the people he loved, rather than hide away. Unlike the Doctor, John was willing to take up weapons when the situation called for it (Although the fact that he was fighting animated scarecrows rather than living beings may have contributed to this). However, it should be noted that while he raised his gun towards the scarecrows, he is never actually shown firing it, hinting at a similar disdain for arms as his alter-ego. (DW: Human Nature/The Family of Blood)

Skills and Abilities
Though wholly human, Smith displayed some skills unusual for a human, such as his intuition that a cricket ball, correctly thrown, would start a chain reaction of events that would save a woman and her baby from being crushed by a falling piano; perhaps this was a lingering trace of his Time Lord self. (DW: Human Nature/The Family of Blood)

Behind the scenes

 * Smith's parents Sydney and Verity were references to Sydney Newman and Verity Lambert, both essential to the making of Doctor Who.
 * In contrast to the Seventh Doctor's version of John Smith in the original novel of Human Nature, who generally appeared drastically different from the Seventh Doctor in personality - such as his inability to improvise plans and his willingness to express emotions - while retaining some of the Doctor's essential core beliefs - such as his refusal to use weapons and his open-mindedness about issues such as skin colour - the Tenth Doctor's John Smith persona was more of a product of his time - willing to use weapons and occasionally bluntly dismissive of Martha Jones due to her skin colour - while being relatively similar to the Tenth Doctor's basic personality in areas such as his tendency to talk a lot when excited and his willingness to express emotions.
 * In his video diary (released with the Series 3 DVD set), David Tennant remarks that the makeup used to make him look elderly (in the "alternate future" sequence) made him look uncannily like his real-life father.