From Longman Dictionary of Contemporary Englishwhat makes somebody tickwhat makes somebody tickinformalCHARACTER/PERSONALITY the thoughts, feelings, opinions etc that give someone their character or make them behave in a particular way I’ve never really understood what makes her tick. → tick
Examples from the Corpus
what makes somebody tick• After working with him for five years, I still don't know what makes him tick.• Try to figure out what makes him tick.• Who are these men and what makes them tick?• As a teacher, you need to get to know your students, find out what makes them tick.• Nobody can figure out what makes him tick.• But they also have ideas about how the social world works and what makes its inhabitants tick.• He's always been interested in what makes people tick.• It's like reading a biography of a favourite author to learn what makes them tick.• Jody has thought a lot about what makes Red tick.• I would listen to what makes you tick and what you like and then be me with those characteristics.• But identifying them, learning about their behaviour and distribution and understanding what makes them tick, requires some enjoyable investigation. 