Betrayer
At first, I could do it with the force of will, but a year ago I had to borrow my sister’s old med school textbooks and the internet to search for something stronger.
I had first considered things like morphine but being so addictive I figured becoming an addict could be worse than actually shifting. It took me a while but finally, I figured out a special cocktail of muscle relaxants, sedatives, and traces of wolfsbane that would prevent me from shifting by forcing my body and mind to become very relaxed, almost to the point of going to sleep.