Mandelbrot Transfer
A Mandelbrot Transfer is when a typical mortal human or animal is made extrafertile or extrasterile by making physical contact with a highly extrafertile or extrasterile individual.
Mandelbrot Transfers can occasionally occur accidentally when the individual with higher fertility or sterility is untrained in the art of withholding it.
The duration of physical contact required to enact a Mandelbrot Transfer varies depending on the sheer quantity of fertility or sterility involved. If one has an enormous quantity, the Transfer can occur within milliseconds; conversely, one who only has a mediocre quantity needs prolonged contact to successfully transfer.
Research on the subject is ongoing, but currently it is believed that there is a minimum quantity of fertility or sterility required to enact a Transfer. One who is only slightly extrafertile (say, they have an fertility value of merely 10), the rate of flow would be so slow when applied to someone of equal or lesser fertility that it wouldn't even be noticeable unless years of undisturbed contact were to occur.