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.
See also: make, tick, what
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

what makes someone tick

what motivates someone. informal
See also: make, someone, tick, what
Farlex Partner Idioms Dictionary © Farlex 2017
See also:
References in periodicals archive ?
But what makes someone tick and why are you spending time with him or her?
A: It's very easy to play someone who's just bad, but then hopefully understanding what makes someone tick. I think an exploration of jealousy amongst women is an interesting thing to explore on screen.
Finding out what makes someone tick, linked to business or romance, puts you ahead of the competition.
It often takes a year to really find out what makes someone tick and if there's a long-term future for you as a couple.