That's such a specific intersection, huh? Character vore books that lean into transformation and suspense... most of what I've seen in that niche tends to prioritize the body horror or the, well, consumption aspect above all else, and the suspense gets lost. A lot of them rush to the 'act' and then the story sort of deflates. The ones that get it right, though, build that creeping dread.
There's this one, 'The Hollow Inside', that comes to mind. It's less about the graphic moment and more about the psychological unraveling of the predator character who's slowly transforming into something else entirely as they grapple with their urges. The suspense comes from not knowing if they'll give in, or if they'll be discovered. The actual vore event is almost an afterthought, which is weirdly more effective. The transformation is both physical and mental, a real descent.
Another angle is stories where the one being consumed undergoes the change, like a slow assimilation. That can create a different kind of tension, a dreadful inevitability. You're watching a character lose themselves piece by piece, and the suspense is in the 'how long' and the 'will they escape'. It's harder to find, but when it's done with a slow-burn pace, it sticks with you.