The concept was expanded on in the live-action spin-off "", where characters often use the word "Quickening" to refer to the process of when an immortal's energy is released after death and absorbed by the immortal who killed them. The TV series also cemented that the transfer of Quickening energy included a transfer of some knowledge and skills. The series producers stated, "The power of the Quickening is the equivalent to a major electrical storm hitting—windows explode, lights short circuit, it is almost as if the victorious Immortal is in the center of a lightning storm." Across the franchise, a side-effect of being born with the potential for immortality is that the person cannot biologically have children.