This is actually a hilarious thought I haven’t shared yet :)
Wait for it… trolls and orcs, despite their brutal appearance… originate from herbivores.
The idea came from basic knowledge of biology, evolution, and well, common sense. And the key argument will be: teeth.
Carnivores have fangs – protruding from upper jaws. Think of tigers, wolves, dogs, sabertooths, even cats – every carnivore species has a pair of long upper jaw fangs. Mother Nature, in all her wisdom, designed them to break the spines of their prey. To leap and attack from above.
On the contrary, herbivores can often boast with lower jaw fangs, or tusks. While these could certainly be used for defence, the major purpose of them is: digging and managing roots and other vegetation. Elephants, boars, every other creature with distinctive lower jaw tusks work this way.
So, uhm… However brutal they look, the species were originally vegan. Deal with it :)