if you get maid tf u can't turn into koi. You need to either lose to oberon to become Lois for the female koi tf, or not lose to oberon to stay male for the male koi tf, at least in version .6.
anyways maid tf, if you r lewis and u get turned into a maid you keep ur brain mostly, and later on you will be able to turn others into your subservient maids. If ur Lois tho, you get turned into a willing subordinate and you don't have that option, just bringing others to become fellow maids, not beholden to anyone but your mistress.