Sex Gas

Sex Gas is a type of intelligent gas which came to Earth in an asteroid.

In its natural form, the sex gas is a thick purple gas with high quantities of vorax and ceranium. It can't survive in the atmosphere of Earth for very long and will quickly turn into a pink powder. It can briefly survive inside a Human, though it will eventually kill the host.

While inside a Human, the sex gas causes a variety of changes, both mental and physical. The host gains an enormous sex drive, since the sex gas can feed on the energy produced during the sex. Although sex gas can feed on energy from other sources (such as from the Heart of the TARDIS), the one on Earth found that the energy produced during sex was the best. This sex is fatal for the other participant, since they will be disintegrated and absorbed at the climax. As well, the host will develop special pheromones which are irresistible for other members of the species of either gender. Internally, the heart and brain will increase in size and the lungs will shrink, which will evenutally explode. (TW: Day One)