Doctor Terminal was diagnosed with Einstein Syndrome, a rare disease that eats a person from the nervous system to the brain. He was given two months to live by doctors, so he created a device that can convert matter into energy that will feed the disease and keep him alive. He then returned to his doctor's office and devoured the doctors with his device. He was incarcerated and escaped by absorbing a reporter, the cell bars, all the gaurds, the prison warden, and the carnations near the front gate. He later kidnapped 00.03 The Rumor and devoured her left arm before being defeated by Spaceboy. He battled the Umbrella Academy time and time again till he was sent to the Hotel Oblivion by The Monocle. he vowed to return and destroy the world. He also left behind the Terminauts to destroy the Umbrella Academy should they ever reform.
Doctor Terminal had a device attached to his chest that converts matter into energy to feed his Einstein's Syndrome. It can seemingly convert any matter into energy, and without it he will die.
Apocalypse Suite: Dr. Terminal's Answer