(one's) true color(s)

(one's) true color(s)

One's true or honest beliefs, thoughts, convictions, biases, desires, etc.; one's real personality, character, or disposition. Dave said all along that he only wanted this deal because it was in the company's best interest, but he showed his true colors once he realized that he wouldn't get any special commission for his efforts. You will really see your friends' true colors when you call upon them in a time of crisis.
See also: true
Farlex Dictionary of Idioms.

someone's true colors

Fig. a person's true attitude, opinions, and biases. When he lost his temper at his wife, I began to see his true colors.
See also: color, true
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

true colors

see under show one's true colors.
See also: color, true
The American Heritage® Dictionary of Idioms by Christine Ammer.

your, his, etc. true ˈcolours

(British English) (American English your, his, etc. true ˈcolors) (often disapproving) what a person is really like: Once he got into power he showed his true colours.
See also: colour, true
Farlex Partner Idioms Dictionary
See also:
  • (one's) (true) stripes
  • (one's) true colours
  • at the back of (one's) mind
  • at the back of your mind
  • be in a world of (one's) own
  • be, live, etc. in a world of your own
  • be remembered as (something)
  • be remembered as/for something
  • be written all over (one's) face
  • be written all over your face