(someone) stood motionless
When something is not moving, you can say that it's "motionless".
Use the phrase "___ stood motionless" to describe someone who is not moving because they're surprised, because they're waiting patiently for something, or because they're trying to hide from someone.
He was standing motionless next to the water, looking out over the waves.
This is the kind of phrase that writers use in novels or articles. You can also use it when you're telling a story.