"How do you think I feel seeing you eat a salad??"
A die-hard vegan's ship crash-lands on a planet that's what appears to almost be a haven world, lots of small animals, lots of plant life, absolutely paradise. Except...that the vegan sees a plant suddenly snap shut when an animal gets too close and the animal is eaten.
The cogniscents there are green, skin, hair, eyes, and they move with a slight rustling. They are descendant of carnivorous plants that have learned to become intelligent to survive. -- Fighting Fit
Some cogniscent beings just naturally come to blows. Be it conflicting biological needs, conflicting environmental necessities, or conflicting ideologies. It's just better for everyone if they're kept at least forty SDU away from each other at all times. Some... do not have that option before they discover each other.
Human Lass was from the Ethical Superiority of Vigann. Ze had left to become a missionary of sorts and spread the good word of a clean, plant-based existence. Once the entire universe was completely in harmony, there would be no more need for wars, violence, or any nasty feelings at all. It was a lot of work to reform the universe, and Vigann made sure it was always sending out explorers to spread the good word.
It was astonishing how many cogniscents refused to listen to it. They used utter nonsense like the phrase "obligate carnivore", or "unsustainable aspirations", or "ridiculous pseudoscience." Lass was not discouraged. For every two hundred die-hard unbelievers, there were as many as seven who could be convinced to begin cleansing themselves of the alleged necessity of animal abuse and the products made from it. That was until she crashed on the Phloranian colony P'taal.