CODEX:
Boekind.
Rassillion had done the same procedure, which resurrected fallen Time Lords, to bring back The Doctor's companions... turning them into Time Abnormalities.
Then turned them into a new race of Boekind. Perfecting the accident that made the original, into a proper race.
Their very nature, between fixed point and Time abnormality, created a temporal backlash, that went unnoticed by most. However, it strained the Gallifreyians to be near them.
This backlash is so harsh, I can feed on it, just by binding the Boekin to my realm. Although they are more filling, when actually inside my realm, they don't truly need to be. Just the connection to my soul, feeds me.
• Magic :
Through genetic engineering, Magical pathways were grafted to the former companions. Which allowed fixed point energy, to be passed down to their descendants.
Their entire bodies act as the Arcane focus. So they can channel various bloodline like abilities, as spells.
They can replicate a lot of meta-human abilities, and even Shinobi Bloodline Traits, as spells. It just has to be an ability, tied to their physical body.
They can't use Transfiguration or Alteration, unless on themselves. They can't even use Harry Potter style vanishing spells, without a wand. But they can spit out a mud slide, or a fireball. They just have to get the incantation right.
Rassillion did upload how to use their powers, into their minds.
• Pheromones :
Men of the 51st century, possessed evolved pheromones, making them naturally nice-smelling, and even attractive to others Sapient species.
Modified Boekin, created by Rassillion, share this ability, but take it a step further. Able to manipulate their pheromones, in order to trigger controlled hallucinations, or even hide their scent.
• Male pregnancy :
Jack Harkness was part of a human subspecies, whose males could get pregnant. And Rassillion expanded that to all Boekind.
• Immortality :
After Jack Harkness was first killed, by Daleks, he was resurrected by the Bad Wolf, formerly Rose Tyler. While using the power of the Time Vortex to restore Jack, Rose couldn't totally control the power she wielded, and she brought him back forever by accident.
As such, Jack became a fixed point of time, a moment in history that must always exist. This gave him immortality, but through a means Time Lords have trouble looking at, and even the TARDIS tried to get rid of him.
Rassillion, with Jack's consent, studied this power to resurrect infinitely after Death, without need of regenerating. Even improved it, so Jack stopped aging.
Then graphed the power to all the Doctor's former companions, after realizing regeneration energy, prevented Gallifreyians, from having fixed point energy as well.
The Boekin's new magic powers, allowed the energy to be passed down to their descendants.
With kids maturing to 15 years old, before their aging slows. Then they stop aging at 42 years old, when they are the equivalent of 25.
This was all by design.
• Boekin "Super" Form :
Boekin can transform into a leathery humanoid, with small tendrils in their hair, ending in glowing blue pods.
This form increases their magical and physical power, by a factor of 50. With each "Level" doubling that increase. With Boekin able to increase their Super form's "Level" infinitely. It merely takes time to charge up each level, and they need to train to unlock each powerup, which can take years of martial arts training, per each new level.