A very inept rabbit: the slaverabbit.
Slow and stupid, the slaverabbit never fully grows all their fur, apart from a curious tuft on their head. Their ears are malformed, so they are unable to make out sounds as they should. They also, unfortunately, never grow their tail which means they look especially ugly. All of these faults are compounded by the fact that they grow freakishly tall and especially loud.
The slaverabbit doesn't understand how to rabbit, so must be coerced into adequate behaviour. This includes making sure they groom you (but without their tongues), learn how to produce appropriate foodstuffs (pellets! fibafirst! banana!) and be the one responsible for cleaning the warren (under heavy supervision, of course).
Although they are very much hard work, given enough time and training, this poor excuse for a rabbit can at least become somewhat of a use.