The word "most rascal" is an uncommon phrasing and is not typically used in the English language. However, if "most rascal" was meant to indicate a mischievous or unruly individual, potential antonyms could include well-behaved, responsible, or respectful. These terms convey an individual who behaves appropriately and adheres to societal norms, rather than flouting them. Other antonyms might include obedient, dutiful, or honorable, indicating someone who follows authority and acts with integrity. In general, antonyms for "most rascal" describe individuals who behave in a manner opposite to that of a troublemaker or rogue.