Linarian sought out the deep recesses of the world, and studied the cycle of life and death, teaching it to those willing to venture into his subterranean habitat. Linarian was born to the angel Inarius and the demon Lilith, who, among their followers, had escaped the Eternal Conflict of Heaven and Hell to create Sanctuary. He then established the Priests of Rathma along with founding necromancer Kalan, ensuring the Balance would forevermore have its protectors even if the world could not remember the events that nearly destroyed it.

Subsequently, he was one of the few residents of Sanctuary able to recall the events of the war, which was assumed to be an allowance for the original nephalem due to their highly advanced ages by that time. Rathma was a key participant in the Sin War, acting in the shadows alongside the mystical being Trag'Oul to sabotage both his parent's causes and preserve the Balance by ensuring that neither his parents nor their respective races could dominate the future of the world. Rathma's parents were the ringleaders of Sanctuary's creation, Lilith and Inarius he balked against their different yet equally domineering ways from an early age.

The Chosen (mentioned only) Rathma, whose birth name was Linarian, was a first-generation nephalem and tutor to the first Necromancer of his namesake's order, the Priests of Rathma.

Why would rathma help lilith? diablo 4