Following the events of Episode 7, the First Order is desperate for new technology to gain an upper hand against the resistance. The two forces are roughly equal in strength now, but the Resistance has the sympathies of the people whereas the First Order still focuses more on control and order leading to brutally putting down uprisings within their territory. Having lost the Starkiller base, the main leadership of the Empire has shifted to the planet Wayland, where the dead Emperor's' main research base was hidden within Mount Tantiss.
Mount Tantiss is a veritable treasure hoard of secret and often forbidden technologies, tucked away for one reason or another. Following the Empire's original demise, the planet Wayland was lost to the New Republic, but the First Order captured the planet back and made it the center of their new empire shortly after the destruction of the New Republic seat of power at Coruscant by the Starkiller base. Supreme Leader Snoke discovered Mount Tantiss and is now having trusted men sift through the various technologies for anything to give an advantage against The Resistance, even if those advantages are deemed immoral and inhumane.
One such technology was a curious implant that attaches to the brain stem of various humanoid species. Humans have the largest success rate with the implant, while other races have slightly diminished successes with it. The implant allows the mental transfer of a consciousness to another body with an implant and identical DNA makeup. Essentially, when the host body would die, the mind would be preserved and be transferred to another body to live and fight again. This "immortal soldier" technology as it was termed became of special interest of Snoke, who put more and more resources into the project.
The tactical advantage of this technology was significant. After all, the most expensive cost in an army was training it. Training a single stormtrooper from an early age had significant costs, anywhere between 500K to a million credits depending on their role on the battlefield, and an average of a third of typical stormtroopers would not survive their first major battle. Only about fifteen percent of stormtroopers would last five years of typical service, and so training costs of constantly retraining an army was immense. For the mind to be preserved after the body's death meant that they only had to train a soldier once, and that each death would give new experience.
As the project matured, Snoke had the most elite of his soldiers singled out and selected, keeping an eye on them and judging their talents and skills, and eventually assembled them into their own separate division. Thus was born the Valkyrie Division, a group of twelve extremely talented soldiers formed as an experimental squad, the most elite group of soldiers in the entire First Order.
