Stranglehold

It is so difficult to select the right candidate for super soldier serum.
Almost as difficult as it is to develop a serum that will assist every cell of the body to do what it does better (without throwing off the delicate balance and making viability impossible). Once he had a small menagerie of super dogs and super apes, and he had a serum which every computer simulation said would work on a human woman (and maybe some human men but with a significantly reduced lifespan), then he only needed the right candidate.
Firstly, someone who could keep a secret.
He was certain she had all the qualifications. She had the leadership skills, the discipline, the military training, a flawless body, and her heart was in the right place.
Then, when he showed her the affirmative test results, suddenly his heart was in the wrong place...
... in her hand. She set it on the lab table, still beating, and warmed up the operation table to repeat the procedure on another of her choosing.
e·vil /ˈēvəl/ Conjuring one's individual benefit at the expense of any or all others.
Synonym: Wicked.
Antonym: Stupid.