Luke Smith

An artificial Human, The Archetype was the creation of the Bane. Less than a day after his birth he met Maria Jackson, helped to defeat the invasion plan of his creators and received a name, Luke Smith and an adopted mother, Sarah Jane Smith. He resembles a boy in his early teens.

Profile
The Bane had trouble getting 2% of the Human population to accept Bubble Shock!'s "special ingredient" and so they created the Archetype from thousands of samples of various entrants to the Bubble Shock! tour (including Maria Jackson and Kelsey Harper) for the purpose of perfecting the formula so it would appeal to the entire population. However, when Maria inadvertedly sets off an alarm by using her mobile phone, the ensuing events cause the Archetype to awaken and escape, joining Maria and Sarah Jane and instantly befriending them. Later he effortlessly memorises a very long string of numbers that he uses to defeat the Bane, and destroy the Buuble Shock factory.

After Sarah Jane suggested several names, including Alistair (after the Brigadier) and Harry (after Harry Sullivan), Maria thought of Luke. Sarah Jane had Mr Smith create adoption papers for Luke and took him in as her son. (SJA: Invasion of the Bane)

Over the next few months Luke slowly learns about the world around him, and successfully aids Sarah Jane, Maria and Clyde Langer in combatting alien threats on several occasions. He demonstrates exceptional intelligence and eidetic memory which, while being a great asset to the team has also been a problem, such as when he inadvertedly aided the Slitheen in their plan to harvest the energy of the sun. (SJA: Revenge of the Slitheen)

He is given an ancient talisman by an elderly woman and told to keep it a secret, but is exposed by Mr. Smith. Knowing the importance of secrets he expresses guilt at not keeping his, but is ultimately pleased with the outcome as the talisman is actually a key to a portal that allows evil Gorgons to enter our world. (SJA: Eye of the Gorgon)

When he is inadvertedly captured by the Uvodni General Uvlavad Kudlak along with Clyde, and several other teenagers from around the country, he successfully escapes from imprisonment on the alien ship and ultimately exposes a plot by the Mistress, thereby freeing the captives. He earns his first kiss from one of the captives, Jen, to which he is bewildered and confused. (SJA: Warriors of Kudlak)

During the events of Whatever Happened to Sarah Jane? Luke appears to cease to exist, as Sarah Jane was killed at the age of 13 and therefore was never there to rescue him from the Bane. He is returned to the timeline at the end of the story along with his mother.

Mysterious TV reports are later seen by the team which seem to imply that Luke is actually Ashley Stafford, the child of Jay and Heidi who has been missing for three months. While Mr. Smith initially confirms that he is a genetic match with the missing boy, and he is returned to his 'rightful parents', it is revealed that Mr. Smith is actually working with the parents, who are Slitheen, to capture Luke and harvest his inherent psychic energy using a headset from the Pharos Institute. He is forced to use the headset by the Xylok to bring the moon crashing into the Earth, but is saved by Sarah Jane. (SJA: The Lost Boy)

Luke was later introduced to the Doctor, Jack Harkness, Martha Jones,Rose Tyler, Donna Noble and Harriet Jones following Earth's transportation to the Medusa Cascade and also aided their efforts to contact the Doctor with the idea of using Mr. Smith to link telephone exchanges and boost the signal. (DW: The Stolen Earth)

Personality
Even in his first hours of life, Luke knew how to speak, but he knew nothing of the world. He tended to respond to anything happening around him with a naïve response, such as "Is that good or bad?". Kelsey Harper had a crush on him but he seemed entirely oblivious to this development.

He quickly builds a strong friendship with Clyde, who, being far more socially adept than Luke, teaches him the 'proper' way to be a teenager. However, his logical and analytical personality mean he cannot tell good jokes, and he has a terrible sense of balance meaning he is not good at skateboarding.

As he spends more time with his new family, he gradually becomes accustomed to morals and gains a strong sense of right and wrong.

To summarize Luke Smith in terms of The Doctor's Companions, he is a cross between Zoe Heriot and Adric.

Donna's World
In the alternate reality created by Donna Noble turning right he went to investigate the Royal Hope Hospital in place of the recently deceased Doctor, along with Sarah Jane, Maria and Clyde Langer, thus meeting Martha Jones. However, since the hospital was moved to the moon, and the Doctor was not there to save the situation the oxygen ran out before the Plasmavore was discovered, causing every one in the hospital, including Luke, to die of suffocation. (DW: Turn Left)