If character traits are not clearly stated how can a reader figure them out

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how the character acts move or talk.

You should observe and pay attention to the way they talk, behave when they are alone, and when they are in somebody's company. Observe what they do, what they like and dislike. Just like figuring out a real person - you should think the character is a real person, and consider how you would figure out somebody in your own life, who is not fictional.