Alternate timeline (A Christmas Carol)

In an alternate timeline, Kazran Sardick was a cruel and heartless man who only cared about money before the Eleventh Doctor altered the past to change Kazran into a better person. This was the original timeline before it was altered by the Doctor. (TV: A Christmas Carol)

A harsh upbringing
When he was twelve and a half, there was an incident where the sky fish attacked Kazran Sardick's school. As Kazran was sick that day, he missed the experience and all of the other children were left with stories while he had nothing. Kazran, a kind-hearted and curious child, became interested in the sky fish and seeing one for himself. However, when Kazran was recording his video diary on his attempts, Kazran was found out by his cruel and unforgiving father Elliot Sardick. Elliot struck Kazran across the face and angrily berated the young boy for what Elliot saw as foolishness. Kazran was left crying all night and would later state that he learned an important lesson that night: no one cares.

Kazran then grew up under the cruel thumb of his father. Now believing that no one cared and with his father as his only role model, Kazran began to become cruel and heartless himself like his father. After Elliot built a machine to control the cloud belt, he gave Kazran control of it as well. (TV: A Christmas Carol)

A cruel and heartless man
By the time he was an old man, Kazran had no heart at all and only cared about money. He was still haunted by the memory of his father who had been dead for over twenty years and kept his chairs facing away from a portrait of Elliot on the wall to avoid all reminders of him. Despite his cruel and heartless nature, Kazran could not bring himself to ever harm a child, haunted by the memory of his own father's abuse.

On Christmas Eve when Kazran was old, he was visited by the family of Abigail Pettigrew who wished for Kazran to release her for one night so that she could spend Christmas with her family. However, Kazran cruelly rejected their attempts as they could not pay the debt that Abigail had originally been collateral for.

At the same time, a spaceship with Amy Pond and Rory Williams aboard was crashing towards Sardicktown. With the only way to save them being Kazran's machine, the Eleventh Doctor arrived while Kazran was arguing with Abigail's family. As he got nothing out of it, Kazran refused to save the ship, but held himself back from striking the family's young son, something that was noted by the Doctor. (TV: A Christmas Carol)

Christmas Eve adventures
With Kazran refusing to help, the Doctor came up with the idea to try to change the man's life using A Christmas Carol for inspiration. The Doctor proclaimed himself the Ghost of Christmas Past and restored Kazran's old video diary so that Kazran could witness the Doctor beginning to change his past.

The Doctor, who warned Kazran that his memories would change as history did, visited Kazran on the night that his father hit him for trying to see a sky fish. The Doctor began his attempt to change Kazran by helping him to see a sky fish as he wanted, but they came under attack by a sky shark that ate half of the Doctor's sonic screwdriver. After the shark was stunned, it was realised that its only chance was to get it into an ice box to transport the shark back into the sky. At Kazran's suggestion, the two awakened Abigail Pettigrew, the young woman who the future Kazran had so cruelly refused to wake up to spend Christmas with her family. Abigail helped calm the shark and the Doctor, Kazran and Abigail returned it to the sky. Before Abigail was returned to her ice box, the enamoured Kazran promised that he and the Doctor would return for her every Christmas Eve. As a result of the changes, Kazran gained a collection of photos of Abigail and a portrait of Abigail replaced his father's in the future.

Over the next several years, the Doctor and Kazran awoke Abigail on Christmas Eve to have adventures with them all over time and space. The future Kazran gained memories of these adventures as time changed around him, remembering both timelines simultaneously. As Kazran grew older, he and Abigail fell in love with each other and kissed after a Christmas Eve spent with Abigail's family. The next Christmas Eve, while at a 20th century Hollywood party, Abigail admitted that she was terminally ill and only had a single more day to live. As a result, a broken-hearted Kazran ended his adventures with the Doctor without explaining why. The Doctor, who realised that something was wrong, left Kazran the broken half of his screwdriver in case Kazran ever changed his mind.

A broken-hearted and bitter man
Over the next few years, Kazran fell under the influence of his father as he did in the original timeline, but this time he was broken-hearted and bitter over Abigail's fate instead of heartless and cruel. Kazran kept Abigail on ice, unable to decide what would be the last day he spent with his beloved. As a result of this change, the portrait of Abigail was once more replaced with the portrait of his father.

By the time he was an old man, Kazran still had Abigail in suspended animation and the broken half of the sonic screwdriver, but he continued to refuse to save the crashing spaceship. In the new timeline, Kazran felt that life wasn't fair and claimed to not care at all. Even after being shown the crew and passengers of the crashing spaceship by Amy Pond, acting as the Ghost of Christmas Present, Kazran refused to relent.

In a final attempt to change Kazran's life, the Doctor brought the twelve-year old Kazran forward in time to see what he would become, effectively making Kazran himself the Ghost of Christmas Future. Kazran accepted that he would die old and alone until he was shown that his younger self had been brought to his present. After the young Kazran mistook his bitter, heart-broken older self for his father, Kazran nearly hit him before being bombarded by memories of his father and his love for Abigail. Having realised what he'd become, Kazran broke down and embraced his younger self, finally changed for the better.

A final day together
With Kazran's life successfully altered, the two Kazrans and the Doctor attempted to save the crashing spaceship. However, the machine would not respond to Kazran and the Doctor realised that Elliot would never have programmed it to respond to the kind-hearted man that Kazran was now. As a result of altering Kazran's past, the Doctor had made him incapable of using the machine to save the ship.

After being presented with the broken half of his sonic screwdriver, the Doctor realised that the only way to save the ship would be to have Abigail sing into the screwdriver and use it to unlock the clouds. A reluctant Kazran released Abigail who sadly greeted her aged beloved and suggested that their last day together be Christmas Day. Abigail's singing, sent into the cloud belt through the half of the sonic screwdriver still in the sky shark, unlocked the clouds and caused it to snow and enabled the ship to safely land.

With the ship saved, the Doctor returned the young Kazran to his own time and left Abigail and the old Kazran the sleigh they'd used in one of their earliest adventures for the two to use on their last day together. (TV: A Christmas Carol)