The cold blade of the knife pressing against his neck is enough to get Tarn to stop thrashing. He's not about to gamble or risk Wash's hand slipping.

Tarn isn't afraid to die-- no he's afraid to be crippled. To live and become a useless shadow of the feared Decepticon he once was. His voice is what sets him apart from the others. It's what caught Megatron's eye all those years ago. If that knife slips and hits his larynx he may as well kiss his dreams for finding a way into the gene therapy trials goodbye, taking with it any hopes of destroying the cetagandans.

"What do you want." He remains perfectly still, staring straight ahead.