One will stay true to one's nature, even if one pretends or claims otherwise. After our breakup, he came crawling back, trying to convince me that he'd changed, but I know that a leopard can't change its spots.
something that you say which means that a person's character, especially if it is bad, will not change, even if they pretend it has I doubt very much that marriage will change Chris for the better. A leopard doesn't change its spots.