A much thicker vine--around 2-3" across--wrapped itself around her waist and wormed its way down towards Anna's bubble butt. The end of the vine produced more of the same slimy sap and began teasing her asshole, working her up and preparing her body for what was to come.
The magnified sensation of the vine slowly circling her ass and producing enough slime to mix with her own fluids dripping off her clit--which also felt amazing--was driving Anna crazy. If she could move she would be grinding her hips against the vine desperately begging it to fuck her or even just to please please please play with her clit. She was being edged **hard** and the vine still hadn't done anything with her ass despite circling it and pressing just lightly enough to almost penetrate her. Almost with reluctance, with a few careful prods, the vine slowly slipped inside Anna's ass with little resistance due to the paralytic. Anna would have came if she was allowed to. The burst of pleasure was incredible and made her see stars. A tremor shot through her body and her ass ever so slightly contracted. The paralytic gas was beginning to wear off although it wouldn't matter at all soon. It would be minutes too late since the plant was almost finished ensuring her captivity.
She could feel every 2 inch segment of the vine plunging inside her as her ass slowly swallowed it bit by bit. Every new segment that slipped into her ass pushed her further and further towards an orgasm that would never happen. Despite knowing how futile it was, she began rocking her hips slightly to try and get enough stimulation on her own to cum. She managed to move a couple inches to fuck her ass a little bit, but the vines quickly tightened on her limbs and her hips preventing her from moving. The plant was very protective of it's new host and didn't want even the slightest chance of her escaping.
Anna lost count of the number of segments that slipped inside her before she felt the segment just inside of her ass begin to engorge. The plant was knotting her, and the segment would dig into her like a barb if she somehow overcame the paralytic and tried to pull it out. Based on what she knew of this plant it had to be 3-4 feet of vine inside her ass right now. Anna felt a couple large globs of liquid get pumped into her, being excreted just past the knot in her ass to travel back up towards the tip of the vine where it would drain. A couple times a minute a new pulse of liquid would be pumped into her.
The purpose of the vine was to consume her excrement and to keep her medicated and tethered to it. It pumped a concoction that included a mild muscle relaxant and a paralytic into her ass along with a decent amount of water for her to absorb. The compounds would be enough to keep her weak as a kitten. The original paralytic would wear off soon, and she wouldn't need the plant to breathe for her. While the vine might not look like it, it was almost as tough as iron. Even high level adventurers had trouble cutting through it with good steel weapons.