Alexa explores her slave with barefoot-trampling, especially his reaction if he gets crushed under her weight.
She steps on his chest, feel him breathing heavier, bounces a little, does it makes some noises?
The he shows him, how she can step on his face.
What offer? It's nice to stand on a face, hehe!
Soon she gets used with the face under her feet, so this will be her main place to stand and to play with.