"The truth," Derek answered, bluntly. "After Kate...I've had enough lies to fill a lifetime." And if he was asking for honesty, he should lead by example. "That's one reason I got...upset, the other night. It felt like...well, after the fact, I realized that I'd let Kate manipulate me in a lot of subtle ways." And it'd angered him to see that Stiles had learned how to manipulate him so quickly, and that he was that easy to manipulate.