"Of course." She rolled her eyes ever so slightly. Jack Harkness was a good looking man, she supposed, but Talia had only ever had eyes for one man. The Detective. There was no one else who could steal her attentions.
"I'm sorry to disappoint, but regeneration is the essential concept." Talia watched as the servants let people up towards the Pits one by one. "They're a natural phenomenon. A regenerative natural phenomenon. They've existed in my world for over a millennia, and likely long past that, but a millennia I can say for sure. My father has been using them for some time."
Talia pointed down to the liquid. "Feel free to touch. As for what they are... there are two people in the world who actually understood them to that degree and neither of them are here. My sister and my father."