Twelfth Doctor

Initially stern and ruthless, but in reality kind and forgiving, the Twelfth Doctor was the first incarnation of the Doctor's second regeneration cycle, bestowed upon him by the Time Lords at Clara Oswald's urging at the end of the Siege of Trenzalore.
Assured of the survival of Gallifrey, the Doctor was no longer chained down by guilt, becoming a less amiable character, as he no longer needed to cover the pain of what he thought was the extinction of the Time Lords, with a withdrawn attitude who habitually questioned his own goodness. He often dispensed with niceties in a tense situation, becoming cold and calculative when needed. However, despite his ruthless exterior, the Doctor was actually deeply caring and empathetic, always striving to help others for the sake of being kind.
It was not until his first battle with Missy that the Doctor resolved his morality crisis, realising he was simply "an idiot with a box and screwdriver" who went around helping others. Following this, the Doctor began to show his lighter side more clearly and forged a closer bond with Clara. After her death, he spent four and a half billion years in his confession dial to reach Gallifrey due to Rassilon's concern with the Hybrid. Seeking revenge, the Doctor broke his own moral codes and unleashed his wrath upon the Time Lords in an ultimately futile attempt to save Clara, losing his memories of her as a price for his reckless actions.
== Biography ==
=== Post-Regeneration ===
After fighting in the Siege of Trenzalore for nine-hundred-years, the Eleventh Doctor was granted a new regeneration cycle by the Time Lords after an appeal by Clara Oswald. After using the energy from the explosive reset that followed to destroy the Dalek forces, the Doctor returned to his TARDIS to complete his regeneration, (TV: The Time of the Doctor) making a quick phone call to Clara, during which he learned his next incarnation would be old and grey-haired. (TV: Deep Breath) Suddenly changing in a flash before Clara's eyes, the new Doctor voiced his surprise at having new kidneys as the TARDIS began a crash landing. (TV: The Time of the Doctor) Crashing in prehistoric Earth, the TARDIS was chased and subsequently swallowed by a female tyrannosaur; when the Doctor brought the TARDIS to 1890s London, the dinosaur was accidentally brought along with it.
After the TARDIS was spat out, the Doctor, in a severe bout of post-regenerative trauma, acted wild and irrationally, until he passed out in front of the Paternoster Gang. Though put to bed to stabilise, the Doctor soon awoke and, hearing the dinosaur in pain, climbed out onto the rooftop and left on horseback when he saw the T-Rex was being burned to ashes. Deciding to investigate, but still suffering a degree of post-regenerative stress, the Doctor wandered the streets of London. Talking to a passing tramp, the Doctor examined his new facial features, noticing that he had seen it before, before trading in his previous incarnation's favourite watch for the tramp's coat. (TV: Deep Breath)
Seeing an ad in a newspaper placed by Missy, (TV: Death in Heaven) which seemed to be a message from Clara, the Doctor infiltrated a suspicious restaurant, where he and Clara learned that time travelling Clockwork Droids, under the leadership of the Half-Face Man, had been harvesting humans to repair themselves and reach the Promised Land. Trying to speak on peaceful terms, the Doctor snapped the Control Node out of his illusion of the Promised Land by revealing the true state of his existence. Conflicted and unsure, the Half-Face Man fell out of his escape pod, either jumping or having been pushed by the Doctor.
The Doctor then redecorated the TARDIS console room and settled on a new outfit. Returning for Clara, the Doctor spoke of the suspicious way Clara had met him in his previous incarnation, only for Clara to likewise voice her uncertainty of the Doctor's identity and asked to be returned home. Attempting to return Clara home, the Doctor ended up in Glasgow by mistake. However, Clara decided to go out for coffee with the Doctor after the Eleventh Doctor called her and encouraged her to help the Doctor through his regeneration. (TV: Deep Breath)
=== Early Experiences ===
Intending to return to Clara with some coffee, the Doctor saved a Combined Galactic Resistance fighter pilot named Journey Blue from a Dalek saucer attack, though left her deceased brother behind in the explosion. After prompting her into asking nicely, the Doctor returned Journey to her command ship, the Aristotle, where Colonel Morgan Blue introduced him to a Dalek that had developed a fault and turned good. Returning for Clara, three weeks later from her perspective, the Doctor asked her if she thought he was a good man, a question that Clara found herself unable to answer, and returned to base to help the Dalek. (TV: Into the Dalek) 
Joined by Journey and two other soldiers named Gretchen Carlisle and Ross, the Doctor and Clara used a moleculon nanoscaler to miniaturise themselves and enter the Dalek, whom the Doctor nicknamed "Rusty". After losing Ross to the Rusty's antibodies, the Doctor discovered a radiation leak from within Rusty and learned that he had turned good after seeing a star being born. Following the radiation, the Doctor discovered damage to Rusty's power source was slowly killing him, and repaired the damage with his sonic screwdriver. However, fixing Rusty's power core resulted in the malfunction that turned Rusty good to be reversed, with Rusty's destructive nature returning, and causing Rusty to go on a killing spree, as well as send a distress beacon to summon the Daleks to the rebels' base.
After getting slapped and lectured by Clara for his apathy, the Doctor realised he could turn Rusty good again by reawakening his memory of the star being born. Instructing Clara to find a way to restore Rusty's memories of the star, the Doctor made his way to the Kaled mutant within Rusty to mind link with him, causing Rusty to see the Doctor's hatred of the Daleks and destroy the Daleks that had responded to his distress beacon. Leaving to continue his crusade against the Daleks, Rusty commented that Doctor would have made a good Dalek before both of them left. After declining Journey's request to travel with him and Clara, the Doctor returned Clara home, both still unsure if the Doctor was a good man, but with Clara convinced he was at least trying to be one. (TV: Into the Dalek)
=== New Adventures with Clara ===
Deciding to give Clara the choice of their next destination, the Doctor took her to Sherwood Forest to meet Robin Hood, though he was sceptical of Robin's actual existence. He was proven wrong when Robin shot his TARDIS with an arrow seconds after they arrived; however, he refused to believe Robin and his Merry Men were real upon visiting their camp. After participating in an archery contest for a golden arrow, the Doctor got himself, Clara and Robin captured by the Sheriff of Nottingham, who had allied with alien robots disguised as his knights.
Escaping, the Doctor and Robin found out the robots were trying to reach the Promised Land, but lacked sufficient gold to repair their engine. Believing Robin was also a robot, the Doctor was re-captured by the Sheriff as Robin took Clara and escaped through a window. Leading a revolution in the Sheriff's dungeon, the Doctor was informed by the Sheriff that Robin Hood was not a robot, just as Robin came to his rescue and defeated the Sheriff. Assisting Robin with Clara's help, the Doctor helped launch the golden arrow into the ship to allow it to escape velocity and explode harmlessly in space. As he departed, the Doctor left Maid Marian, whom he had met in the Sheriff's dungeon, behind to be reunited with Robin. (TV: Robot of Sherwood)
Becoming obsessed with the idea that a creature designed to hide was following him around, and that everyone was similarly being followed, the Doctor began searching for such a creature. (TV: Listen) Still unable to find the creature, the Doctor recruited Clara's help in finding the creature by using the TARDIS telepathic circuits to find it in her past. However, Clara got distracted by a phone call from Danny Pink, and piloted them into his past instead, back when Danny was a child called "Rupert" and living in a care home. Finding a figure under Rupert's bed sheet, the Doctor had Clara and Rupert turn their backs to allow the being to walk out the room unobserved, leaving them unsure if it really was the creature or just another child playing a trick on Rupert.
Returning Clara to her date, the Doctor continued to follow his theory by trying to use a trace of Clara left in the telepathic circuits, ending up at the end of the universe where a time traveller named Colonel Orson Pink had been trapped for six months. Intrigued by how following Clara's timeline led him to Orson, the Doctor returned for Clara and had them wait at the end of the universe for the night, believing it to be the perfect time to find out if the creatures were real. Finding a chance to confront the creature outside the ship, the Doctor sent Clara into the TARDIS and seemed to get a look at what he'd been chasing before the atmospheric shell broke and Orson had to rescue him. As the Doctor was knocked out, and the TARDIS seemed to be under attack, Clara used the telepathic circuits to fly the TARDIS away. The Doctor woke up to find Clara gone, but, before he could investigate, Clara re-entered the TARDIS and made him promise to leave and not find out where they had landed. Afterwards, the Doctor returned Orson and Clara to their own times and, satisfied by what he had learned, underlined the "LISTEN" that had been written on his chalkboard. (TV: Listen)
Persuading Clara away from a date with Danny in favour of other travel destinations, the Doctor received a call from Madame Karabraxos, who requested he free the Teller and its mate from the Bank of Karabraxos, as he had done on the day she met him. Realising the ramifications of this request, the Doctor built up the identity of "the Architect", using this identity to stage a bank heist for him to commit, with the assistance of Clara, an augmented human named Psi, and a shape shifting mutant human named Saibra. Using memory worms to erase the plan from their minds and prevent the Teller from alerting the young Karabraxos, the Doctor and Clara found themselves already in the Bank with their accomplices, their last memory being the TARDIS phone ringing.
Receiving instructions from the Architect on their location, objective, and the Bank's security system, the team infiltrated the Bank. Entering a safety deposit box, the team set of a dimensional shift bomb into a service corridor, where the team found a briefcase containing six teleporters disguised as atomic shredders. Seemingly losing Saibra and Psi to the shredders when the Teller locked onto them, the Doctor figured out that time travel was involved with the heist plan when a perfectly-timed solar storm unlocked the Bank's vault. Retrieving what the Architect had promised Psi and Saibra as payment, the Doctor and Clara were caught by the Teller and delivered to the bank manager, Ms. Delphox. After Delphox left them to be executed, the Doctor and Clara were saved by Psi and Saibra, who revealed the true nature of the "shredders".
Venturing into the Bank's private vault to find his and Clara's reward, the Doctor instead found Director Karabraxos, and discovered that Delphox, as well as a majority of the bank's staff, was an exact clone of Karabraxos. Seeing Karabraxos' hatred of her own clones caused the Doctor to have an epiphany on the identity of the Architect, and he gave his phone number to Karabraxos as she fled from the solar storm about to hit the Bank. Subjecting himself to the Teller's powers, the Doctor regained his lost memories and realised the true objective of the bank heist. Freeing the Teller and its mate to a place to live in solitude, the Doctor then parted ways with Psi and Saibra, giving them their rewards, and returned Clara home for her date. (TV: Time Heist)
Later, the Doctor and Clara were left to the mercy of sand piranhas while chained to posts on a desert planet and rendezvoused with fish people, (TV: The Caretaker) had a dinner date in 1937 Berlin, (TV: Kill the Moon) and outran soldiers to escape in the TARDIS, (TV: The Caretaker).