I like the 2nd idea.
I had an idea similiar to that.
A man finds a gold and silver apple in the middle of the forest, feeling the magic course through him, he gains the ability to augment the bodies of women he has sex with. But after going and bedding with a woman, unknown to him, a succubus, he loses almost all of this power. Now with just a trace of the power left, the elders of the forest, sworn to protect the sacred and magical fruit, only to be used in specific situations, has charged a cat person (neko in this case, cat ears, claws (retracted unless purposly revealed), and tail) with following the human and gain the power back from him. The neko falls in love with the human immediately after he gives her shelter and food, after she has searched and searched for the man and was close to starving, unbeknownst to her, he was the one she was looking for. She is later told that the man she is with by a cat informant that he is the one she is looking for, and she is to extract the last bit of the power from him. but each time he doesnt release it to her until after he finds out she is love with him, and he is in love with her as well, climaxing at the end when both profess their love for each other. Upon doing so, the last of the magic augments the neko cat into a human, removing the magic from the man permanently.
I thought of a sequal as well, where both are tracking down the succubus to retrieve the power she stole and currently wreaked on men across the world, but that is a RP for another time heh heh.
pm me if interested in something like this. =)