The Master's birth name was Koschei and he was born on Gallifrey to Drusus, a wealthy Gallifreyan governor, and Maxta, daughter of one of the Lord Presidents. He attempted suicide as a teenager, due to the drumming in his head, in this incarnation, but was saved by his best friend Theta Sigma (The Doctor). After Theta Sigma saved his life, Koschei regenerated into his next incarnation.
The Master was born in his fathers estates near Mount Perdition, on Gallifrey. He was named Koschei, in honor of his maternal grandfather, Lord President Koschei. Young Koschei learned how to walk when he was two years old, and how to read when he was five. By the time he was seven, he recited poetry, and began attending an academy for young Time Lords, which Thetatropolousvsgholtazsr Sigmaakronosvexsithkada (nicknamed Theta Sigma, because his name was difficult to pronounce), who would later become The Doctor, also attended. Koschei and Theta Sigma played near the fields of red pasture near Mount Perdition as young boys. Koschei also went fishing and swimming with his father, Drusus, when he was young.
At the age of eight, Koschei looked into the Untempered Schism, in the Time Lord Initiation Ceremony. This was when a time lock was placed on Koschei, so that he would be a link for Gallifrey to escape the time war, much, much later. Koschei went mad, and heard drumming in his head all the time. Koschei broke down in tears, having fits in public at the academy. He was bullied mercilessly at the academy, so he stopped going to the academy, and his mother had a private tutor teach him. He refused for anyone to see him, and shut himself away all the time. The tutor gave up on trying to teach him, and instead, Koschei taught himself. He memorized every single Gallifreyan poetry book, math book, and history book that his father owned. What happened to him when he looked into the Untempered Schism, had also made him intelligent for a child.
He remembered everything he learned then, but this ability vanished over time, and he had a normal learning ability to others of his age. It seemed to have been temporary.
No one could reach out to Koschei, and he spent years isolated, locked in his room, refusing to see anyone. Koschei even attempted suicide when he was 15, because of the drumming he heard in his head, but he was saved by Theta Sigma, who broke into his room and wanted to save him. The dying Koschei was saved by Theta Sigma, who helped him regenerate, by injecting him with an "emergency serum". Koschei was sweating and had turned very pale, unhealthy veins were also showing up on his body, but his skin glowed orange and he healed.
Koschei's face then flashed with orange light and he had regenerated into his second incarnation. At the beginning of his second incarnation, he decided that he would no longer be isolated, and would try to ignore the drumming in his head. He decided he would pursue a career in politics like his father, and also attend the academy once again. He had blonde hair whenever he first regenerated into his second incarnation.