Hypnotism hadn’t worked, neither had the extended aversion training (although it had left its marks). So she resorted to the only solution guaranteed to prevent her slipping over the edge.
The serum was injected directly into her brain, the nanobots seeking out the amagdala and cerebellum, insinuating themselves so they would block the very final moment of climax.
Her nucleus accumbens would be put into a continually excited state so that edging would release unprecedented levels of dopamine to reward all her future failed attempts at orgasm.
Finally her temporal lobe was commandeered. Something that would lead her to a state of ongoing arousal that was a hundred times worse than anything she’d known so far.
Her eyes also turned green. That was temporary.
Everything else was permanent and irreversible.
Inspired by this great GIF by sleepystephbot