Lerith has use! Granted, one use should not be used because it is unuseful FIRE and we don't want to burn the city to the ground. :(

He will be interested in the plants and at first, he'll be interested in the Thorntooths, too. Look, he likes animals so he'd like those girls that sees a giant wolf and goes [Can I pet your puppy?!] okay.

Then he'll hide from them the rest of the time, and try to research new plants to figure out positive and negative effects. Maybe find medicinal things with them that could help the medical people or something.