With the advent of modern medicine, technology, and genetic science, it is now known that many imbalances in the brain are caused by chemical fluctuations, which were previously mistaken for demonic possession or social dysfunction. A Kindred who is knowledgeable enough about biology can modify a subject's chemical template by causing minuscule changes to the amount of a chemical in their brain. Depending on their skill, very drastic changes could be wrought unto another's mind this way.

Note: This power functions differently from Dementation. Chemical Alteration is permanent, although the changes it brings may be treated with modern psychology and medication. It cannot be used on Kindred. Something else powers a Cainite's mind besides mere chemicals. Also, a vampire must have a Science rating of at least 3 before this power can be learned.

System: Spend a Willpower point and make an extended Intelligence + Science roll. Difficulty depends on the desired change. Causing minor quirks, like mild hallucinations, is difficulty 7. Schizophrenia and other full-blown psychological maladies are generally difficulty 8 or 9. Sexuality can even be changed with Chemical Alteration. The subject could find herself attracted to the same gender, neither gender, both genders, or something truly bizarre, like animals or trees. Modifications like this are generally difficulty 9 or 10. In order for Chemical Alteration to succeed fully, a number of successes must be rolled equal to the difficulty times two.
If the Kindred stops or is interrupted before the process is complete, then the subject has a milder version of the desired affliction, depending on how many successes were achieved. If the Kindred wishes to finish what he started later on, he needn't roll the whole amount of successes again, only enough to make up the successes he missed the first time (he does have to spend another Willpower point, though).