Mewtwo was seething, though it manifested as harsh, noisy breaths and a dark glare fixed firmly on Payne. He could easily level the entire building, free his clones from the Institute, and flee to parts unknown. The urge to shed the restraints like a winter coat and blast off through the roof was almost irresistible.
He moved his glare from the prosecution to the defense and saw Quickie's pained and worried expression. She looked tired. No doubt she was awake all night, preparing for the case. No doubt even longer. Quickie wanted Mewtwo to be safe, and if the outcome of the trial was in her favor, it would mean that Team Rocket wouldn't bother them. They would lose custody, and for all intents and purposes, Mewtwo would be a free Pokemon.
Mewtwo's gaze dropped to the floor. He had to play by their rules. He had promised his clones that he would prevent any harm to them, and he emphasized that he was forced to act within the constraints of human law. Thus, he needed to maintain control. He needed to maintain control for their sake, for Quickie's sake, and for his own.