Roughly

The vine **** hard down through her mouth, breaking through the meager defenses she had. It thrusted down, with little regard for the friction between it and her inside. Alison was unable to speak and breathe. She tried coughing as it went deeper down, feeling some soreness. The vine fit tightly, leaving little space in between it and its new sheath. She tried to move her arms, hoping to grab it and pull it out, but they were well restrained. Alison knew at that moment she had lost an important battle, and despair began seeping into her mind. What was going to be her fate?

She desperately tried to fight for freedom as a last ditch effort, threatened by the fact that her air supply had been cut off. She wriggled and threw her weight around, all the while remembering to keep her legs sealed. But all this action drained her far quicker than before, and she became weak. As a result of all that effort, came her **** attempts at breathing, which merely opened up space for the vine. It filled up as much space as it could.

Alison was now in a place just short of unconsciousness. For some reason, she wasn't fully passing out, as if the vine was producing air for her, maybe not enough to be comfortable, but enough to keep her conscious. I didn't... can plants even... no they... they make enough?..., her thoughts were barely coherent to herself.

Seeing as it found another dead end, the vine prepared to repeat the one strategy it knew, repeated prodding until it found more results. The rest of its body following suit, it pulled itself out of Alison a few inches, before lunging back forth, repeating the motion

Alison had **** but to relax her throat and open wide. It hurt less as the vine pounded down her mouth. It would be incredibly humiliating to Alison that she was reduced to a cock-sleeve, if her mental capacity wasn't diminished for the little air she was getting. She would never in a million years be caught drooling, but with the vine pounding hard in and out, a little bit leaked out with it. Her throat visibly bulged with the movements of the vine.

In and out. In and out. Alison's entire world right now was reduced to her throat. Hoping for the pounding to get softer. Or stop. Or leave her body entirely. But there was little room for those thoughts. Her mind was busy processing the feeling of the lubricated vine rubbing the inside of her mouth, a place that used to be locked away from everything except food and air.

A new vine creeped along one of its kin that hung onto Alison's leg, hoping to explore the place of interest that the vine before it tried to explore. The crawl along Alison's body was a bit difficult and slow, for her body swung as the invader of her mouth thrusted hard into her. But the new vine made its way to the position near her hips. The area was sealed, but it had its kin to help.

As if receiving some silent signal, the vines wrapped around Alison's legs pulled hard in opposite directions, spreading them and leaving her pussy out in the the open. The newcomer got closer to their desired location, resting its head on top of the cave that Alison so desperately wanted to protect.