He saw that the light within the crystal had become a slight flicker.

There wasn't the slightest flicker of fear in her eyes.

I saw the assumption in her eyes, the slight flicker of concern.

He had noticed a slight flicker in her eyes when he'd mentioned "intelligence network."

There was a slight, momentary flicker of interest in the eyes.

He offered his hand in return, but he was watching the eyes, and saw a slight flicker.

His only response was a slight flicker of his eyes.

He saw the first slight flicker of uncertainty in her eyes.

There is only the slightest flicker of movement in her face.

Not that she's got the slightest flicker of the White about her, at least according to your mother.