There is a comment in the game guide that Leona is a carnivore (“Round ears that face forward, as he is a carnivore”), and it seems this might be meant to be taken literally: Leona says “carnivores only eat greens when they’re physically ill” to explain his dislike of vegetables, and “Telling a carnivore to eat greens is like saying, ‘Hey, go give yourself indigestion.’”
Ruggie seems unaware of this, adding vegetables to Leona’s plate ‘(“Stop whining and eat them”), but Ruggie has said he will eat anything as long as it isn’t rotten so it is possible that he just does not know of Leona’s dietary restrictions and/or is mistaking them for pickiness.
Vil is not pleased by the barbecue that Leona arranges during the Cloudcalling event (“It’s ALL meat!”). Leona says, “Looks normal to me?”
Leona gives Ortho a poor grade during Master Chef for the chef’s decision to add vegetables to the dish he orders. Ortho is undeterred, saying, “(Leona) decided it wouldn’t taste good based purely on visual information. Presentation, flavor, nutrition…so many different factors to manage! This is going to be even more difficult than I’d imagined. What fun!”
Leona has several lines of dialogue about his preference for meat, telling Ruggie at the end of Book 6 that he doesn’t care what Ruggie makes for him “as long as it’s got some kind of meat in it.”
Leona is one of the strictest judges for Master Chef—on par with Vil—but his ability to identify high-quality cuisine does not seem to mean that he is a picky eater:
Ruggie says that “Leona doesn’t care (what he makes) as long as it’s edible,” despite how he is a literal prince, and during the NBC event he does not balk at the idea of eating snakes, spiders, bats, rats or frogs. Riddle rejects the idea of eating any such things “wholeheartedly” but Leona asks him, “Where’s your culinary curiosity?”
Displeased with Halloweentown’s primary offerings of “salad stuff,” Leona offers to procure his own “non-plant” ingredients, asking about the kind of game he can hunt. This is maybe our first insinuation outside of the prologue (and Vil’s teasing about Leona hunting Grim) that Leona is capable of hunting.
Is it possible that being an adept hunter is one of Leona’s more lion-like traits? Ortho explains that Leona is “a beastman with lion genes” and Ruggie commends on Leona’s “lion’s roar” being capable of cutting through the noisy crowds at spelldrive games.
Idia says, “Lions are supposedly part of the Felidae family, but Leona’s about as docile as an angry lawnmower.”
Twisted Wonderland Reference Note 