You, some random person that you decide who you want to be, have just found the Sex Machine. A small convenient little machine powered by superdiem, a mineral which practically has infinite energy, created by some probably supernatural source after seeing life as we know it and it's ability to reproduce... and how many things end up Fucking things they were not meant to fuck. The desire to procreate is so strong that things try to procreate often fuck things they aren't meant to fuck. Family, Siblings, those that are too young, things in a different species, things in a different kingdom of life, things that aren't living in any sense of the word. Who or whatever was watching thought "You know, how about I give this to them? That way they could fuck whatever they wanted and it would work." Now for some reason you have the Sex Machine.
Made so that even an idiot could handle it there were only two main settings. Fertile or Infertile, and Permanent or Temporary. To activate the Sex machine you think about one target, press the main button, think about a second target, press the main button again, and then let the magic work. What is the magic exactly? Well using some seemingly random algorithm it checks the genetics and body structures of the two targets. After the check it will alter the two subjects so they would be able to have sex the way the Sex Machine's creator thought it was supposed to be. Two organisms of the same species, of a healthy sexually mature age, and are genetically different enough to not be directly related use a penis to thrust inside a vagina. Then after in sexually correct forms the Sex Machine will turn up the two organism's reproductive instincts up to their max, and alter their environment to facilitate sex easily.
If the Sex Machine is set to Fertile then the two organisms that are changed will be able to have offspring, and if it is set to Infertile then the two organisms are changed to be unable to have offspring.
If the Sex Machine is set to Temporary then any changes the two organisms received are reverted, and if it is set to Permanent then any changes the two organisms received are not reverted. Note, on either setting the environmental changes will revert and organisms changed with the Permanent setting are still able to be modified by the Sex Machine.
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Now that we've got the boring definitions done who is up to make the Sex Machine work?