The bottom was taking care of all his younger siblings (parents died I think) he had a problem with his underwear disappearing and he kinda had a suspicion that some one was taking them (I think) then the top os at their house one day, this was their first time meating, the sister let him in (i think) we are led to believe that the top is the one taking the underwear, then we come, (the top moved into the apartment next to theirs) then we come to learn that the top is not taking the undies but instead was a undercover cop the whole time trying to catch the real undie theife. If I'm remembering correctly the top was being really flirty with the bottom the whole time.
Thanks if you can help me :)