Fourteenth Doctor

Sarcastic and Cheeky as well as being known for his wild mood swings; the Fourteenth Doctor is the third Incarnation of the Doctor's second set of regeneration cycles, and the fifteenth Doctor overall. This incarnation of the Doctor was particularly troubled with his first moments being that of murder. When the thirteenth Doctor sacrificed herself for her companions, she regenerated into the Fourteenth Doctor, however, while regenerating, the former companions found themselves erased from history by the Doctor's regeneration streams. The Tardis, which witnessed the killing, cast the Doctor out as unworthy; until he could redeem himself.

This Doctor was by far the most emotionally unpredictable incarnation of the Time-Lord. He was burdened with the knowledge that he killed his friends and thus, he vowed never to travel with a companion again as he could not have more blood on his hands.

While travelling to Cardiff to seek out the help of Torchwood in finding the Tardis, the Doctor encountered a young woman named Hannah Gray who allowed him to hitchhike with her, until he accidentally caused her to crash. She then followed the strange man until he could repay her.

After gaining the Tardis back, the Doctor granted Hannah one trip to thank her but after they fought the Weeping Angels and Vashta Nerada together, he began to feel an emotional attachment to her which he wished didn't exist. He then abandoned her on Earth for her safety, opting to seek out an old friend who he found out was alive.

After finding both Missy and his long lost; presumed dead, daughter, Jenny, the Doctor came to accept he needs someone around to care for. He returned to Earth to seek out Hannah to show her the stars. While she was angry at him abandoning her, he wins her round by taking her to the Birth of the Sun where he accepts he has fallen in love with this irrelevant human girl.

After finding out that the Time-Lords are storming the Galaxy, seeking to enslave the Universe. The Doctor assembles his closest friends, and enemies, to fight back against them before they can start a second Time War. During this conflict, he and Hannah defeated the Time-Lords and cast them out, although at the cost of Missy's life. His daughter, Jenny, abandoned him following his victory, not believing him to be the same person he once was.

Personality
The Fourteenth Doctor had many of his previous forms traits such as the Twelfth Doctors dry sense of humor but he also enjoyed talking a lot, very similar to his tenth and eleventh form, it is also to be noted he could have number nine's aggressiveness and mood at times. At his core, he was tart tongued but humorous, passionate and caring as well as bipolar. He could be very rude to people, although, he admitted to Hannah Gray that he was rude because he didn't want to get attached to many people as that's just another person to outlive. (TV: Torchwood and the Doctor)

Following his regeneration and the deaths of Yaz, Graham and Ryan at his hands, the Doctor began to push away those who tried to get to know him. He was rude and disrespectful as well as very blunt with people, often talking down to them to get them to dislike him. Although, when he met with Jack Harkness, he was shown to soften up and be cheerier around him. (TV: Torchwood and the Doctor)

The Doctor was shown to be a very curious and passionate person, often getting annoyed when he couldn't do things his way, or if he had to wait for things. He had a habit of not standing still as well as his hatred of sitting down. He considered all time precious and was determined to make the most out of every second he has alive. This was rather similar to his eleventh incarnation, who also showed signs of ADHD. (TV: Journey to the Edge of the Universe)

Hannah Gray would often comment about how the Doctor was like a man child and that she sometimes felt more like a mother to him than his friend. He enjoyed using this to wind her up and watch her get frustrated with his immaturity. Although, he was very good at recognizing when he had pushed someone too far. (TV: The Face of Death)