The phrase "gotten into mischief" implies engaging in some form of naughty or mischievous behavior. Antonyms for this phrase could include "behaving," "obedient," or "compliant." These words suggest adherence to rules and regulations, as well as a willingness to follow authority. Other antonyms may include words like "lawful," "moral," or "virtuous," which imply actions that are ethical, appropriate, and morally responsible. Alternatively, antonyms for "gotten into mischief" could also include words like "well-behaved," "reasonable," or "thoughtful," which suggest a responsible attitude towards oneself and others. Overall, antonyms for "gotten into mischief" imply a positive, responsible, and rule-abiding attitude.