"Energia is regularly phantom-like energy that lives in each living thing, even things that are created at the present time have Energia moved into them from the universe like air, it's a wellspring of life. At any point when a hybrid uses their abilities it uses either a significant or insignificant amount of Energia, it functions like fuel." ― Amelia Clementine
As explained by Amelia, Energia seems to be the source of life in all living things, with "Stamina Variable" being the Slang Term. This source of energy was previously touched upon and very prevalent in the first volume, but retconned to similar functions under a different name upon the following of Volume 2. All living thing's possess Energia and it's explained as the main source of a Hybrid's abilities. The way Amelia explains this, Energia converts itself into the ability itself. Faultl3ss has stated that Energia functions to similar to actual energy in the way that it cannot be created or destroyed, but only transformed. Prior to Volume 2, Noah had stated that anything reaching an Energia level of below zero would instantly have death imbued upon it, although this concept wasn't addressed ed in Volume 2 as of yet.