What can you do to make your characters stand out as individuals? Well, there are quite a bit of strategies you can try, but two of the most popular ones to try are to give you characters habits and certain mannerisms. Think outside the box with this. Get creative. I say this because, one of the things you want to avoid is making your characters like everyone else.
Maybe you have a character who, when they are deep in thought, not only creases their brows together, but they also place a hand on their hip and scratch their cheek with the other at the same time. Then they lean on their other hip, place their opposite hand on that hip and scratch their other cheek with their other hand.
Yes, one would normally call this fidgeting, but it is very specific and the reader gets to see just how they fidget. The details of these movements causes this character to stand out. That’s what you want.