He slaps your ass.

There's not much in the refrigerator, but you find a couple of bananas at the back. You are just bending down to reach them. When there is a loud "SMACK" and you feel a stinging pain on your bottom. You give a high pitched yelp of surprise and whirl about to see Kevin, your roomate standing behind you laughing.

"I just could not resist that." He chuckles. "You have a ripe little butt for sure buddy."

You rub your ass, scowling at Kevin. He did not hold back at all and the afterglow of his palm on your soft buttock stings like hell. You push past him, annoyed both because of the slap and because he has finally seen what you like when taking the X-Change pills. Throwing yourself onto the couch you sit crosslegged and peel a bana as Kevin takes a seat in an armchair opposite you.

"You know Alex, you make a damn hot chick." Kevin says grinning. "If I didn't know that was you in there I'd fancy a run at you myself."

Despite your annoyance the compliment pleases you. You are still mad about the slap though and need a way to get back at Kevin. What he just said gives you an idea for this. If you get him to want you despite knowing who you are then you could use that in so many ways to manipulate him.