The same change can be made to the following words to create new ones. Can you determine what it is?

FISHING
DIVE
MARE
POT
FATED
RUG

HINT:
The change involves two letters - the same two for each word.

Answers:

The letters IN can be inserted into each word to create new ones:

FINISHING
DIVINE
MARINE
POINT
FAINTED
RUING

Credit: LA Times Crossword
Sylvia Bursztyn and Barry Tunick
DROPPING IN