The assistant (Modern who)

Bio: Is one of the last time lords; was with the war doctor as the last great time war happened and help the war doctor with the total annihilation of the daleks and part of the genocide of the time lords

The 8th-war assistant:Charming and loving also a pacifist/A warrior

Reason for regenerating: Was with the 8th doctor when the time war broke out and was with him when they were trying to save a young woman from the daleks but when she rejected their help and were all killed by the daleks. They awaken in the company of the Sisterhood of Karin and were told they were temporarily resurrected the sisterhood urge them to bring the war to an end, and give them a choice of elixirs to trigger their regeneration; after contemplating whether or not to do this they decided to drink one of elixir that was designed to produce a warrior.

The war-9th Assistant personality:A warrior/Similar to the ninth doctor.

Reason for regenerating:After helping save Gallifrey with both 10th and 11th incarnations of himself and the doctor both war versions went in the TARDIS and started their regenerations and knew after going back to their places in the timestream they would forget ever saving Gallifrey but none the less they would regenerate into their 9th incarnations. (Day of the doctor)

The 9th-10 personality:Similar to the ninth doctor/Similar to both 10th and 11th doctor and assistant

Reason for regenerating: Was with the 10th during the invasion of the Sycorax and when both the 10th doctor and 9th assistant challenged the leader of the Sycorax for the earth and when the 10th doctor got his own hand severed the leader and forced the leader to surrender and the leader attempted to attack the doctor; the 9th assistant jumped in the way and was the one killed. After the 10th doctor defeated the leader and returned to the TARDIS with the 9th assistant, rose, mickey, and jackie they saw the beginning of the 9th regeneration (During the Christmas Invasion/Series 2)

The 10th-11th assistant personality:Similar to both 10th and 11th doctor and assistant

Reason for regenerating:Also intentionally Radiation poisoning in order to save the life of Wilfred Mott. (During The End of Time)

The 11th-12th assistant personality:Similar to both 10th and 11th doctor and assistant/Similar to 12th doctor

Reason for regenerating: Also neared death from old age after exhausting all of his regenerations, but was also granted a new regeneration cycle by the Time Lords, which automatically triggered a regeneration.(During Time of the Doctor)

The 12th-13th assistant personality: Similar to the 12th doctor/Similar to the 13th doctor

Reason for regenerating: Also electrocuted by a CyberMondan, and delayering the regenerative process. Also later being shot repeatedly by another Cyberman and caught in the same massive explosion, triggering the regeneration further.(During Twice Upon A Time)

The 13-14th assistant personality:Similar to the 13th doctor/ TBA

Reason for regenerating:Also mortally wounded by the Qurunx's destruction beam (During The Power of the Doctor)

The 15th assistance personality:TBA

Reason for regenerating:TBA