The phrase "knows what makes tick" is commonly used to describe someone who fully understands another person's motivation or desires. This concept can also be expressed using a variety of synonyms that convey a similar meaning. Some examples of potential synonyms include "understands the inner workings," "takes to heart," "intuitively grasps," "appreciates the essence of," and "instinctively comprehends." Each of these phrases emphasizes a different aspect of the understanding that a person possesses, from recognizing subtle details to connecting with another individual on a deeper level. No matter which synonym is used, the result is a deeper level of insight into the motivations and needs of another person.