Interpretation: a very close or congenial friend.

Example: We only know each other, but we just talk in general terms, so we can't become friends all at once.

2, the liver and gallbladder look at each other

Interpretation: The liver and gallbladder are closely related and take care of each other. Metaphor is honest communication with each other.

Example: They have lived together since childhood, treating each other with sincerity and never having personal conflicts.