Vampire Bunnies!

Bunnies should have a quest to become vampire bunnies which requires them to kill a number of Human NPCS, Or perhaps bunnies can automatically become vampire bunnies if they kill a certain number of Human NPCs within a certain period of time.

The game can provide flavor texts and certain buff/debuffs warning the bunny when he or she has come close to the quota. For example after killing 100 Human NPCs within an hour a Bunny may receive the debuff (a taste for blood, +10% damage -5% power). This buff/debuff can increase to a second state (blood thirsty, +15% damage -10% power) and the game can warn the player via flavor text in chat, on screen display and/or buff tooltip, that "At this rate there may be no going back"

Once a bunny becomes a vampire bunny they can become white in color and receive a buff at night and a debuff during the day, so that Vampire bunnies will mostly hide in town during the day, and come out to play (kill) at night when their power is strongest.

Additionally, Vampire Bunnies can have a weakness where if they eat garlic ( an item we are sorely missing anyway) they die instantly, and a skill that consumes blood to increase power, or a buff that increases the bunnies power the more humans they kill within a certain period.

The rule of killing humans can be modified to mean killing any beast with blood in it.

Vampire bunnies would no longer be able to eat carrots, but instead they can be given the ability to eat corpses like wolves, (though im not well versed enough in the lore of vampires to know whether or not vampires are known to eat corpses. maybe just *extract blood* skill under skin/autopsy)

To top it off Vampire Bunnies could receive the reverse effects when eating food (food that heals humans, damages vampire bunnies)