The target doesn't move and takes no actions.
A flying creature stays aloft, provided that it is able to do so. If it must move to stay aloft, it flies the minimum distance needed to remain in the air.
Your foe's limbs lock rigid, boots rooting to the earth like iron stakes, muscles straining uselessly against invisible chains. If airborne, wings or spells hold it suspended in place, fluttering just enough to defy gravity's pull without advancing a single inch. The air around thickens, binding breath to stillness, every twitch denied.