You should be able to make trees that have inedible meat or bodyparts or something as fruit in evil biomes.
I can definitely see an evil-biome tree with eyes on it or something, a big brother to the staring eyeballs grass.
But there's no particular reason the fruit needs to be inedible, though it should probably be inedible raw.
"Mmmmm... Urist, you make the best ≡staring tree roast≡ known to the Mountainhome!"
Actually, that's one of the mods I'm thinking of making after the new version comes out: plants both fantastic and mundane (using Dwarf Chocolate as a base). Imagine entering an evil biome and suddenly coming across a grove of purplish, leafless trees, their trunks studded with curious warty growths.
And then they open and reveal they're eyeballs that endlessly stare. Stare, but never see.
And Visus.... that's really... disturbing. But I don't know. Isn't that possible already with mods? But don't worry if isn't, since I'm sure that many eager mods will read that can of worms you just opened and try if not on the current version then on this so much awaited one.
Why, thank you!
Sadly, Eric Blank's right: the closest we can get is transforming the infected creature into another one of the vector creatures. I simply thought of the idea because with growths now available to plants, perhaps we could see a similar mechanic applied to creatures.
It needn't be used for body horror: I can see making a plant-animal that grows fruit on its skin, or something (although maybe that can be done with the current version by making the planimals' fruits a shearable product).