what makes someone tick
what makes (one) tick
The things that motivate one or make one behave in a certain way. I'd love to sit you down for an interview so I can find out what makes you tick. Janet is a very private person, so it's hard to know what makes her tick.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
what makes someone tickwhat motivates someone. informal
Farlex Partner Idioms Dictionary © Farlex 2017