You lived with Peter. Sure, he seemed very perverted and creepy, but you know... boys will be boys. He was just more on the extreme side. He was improving on giving you your space though. After all, he was actually being loved back, and that seemed to be enough to make him trust you.
One morning, you woke up feeling nauseous. You looked to your right to wake up Peter, only to realize that you were at the opposite side of the bed than where you remembered being. Weird. You looked to your left, and freaked out when you saw your own body beside you sleeping.
The sight made you scramble out of bed and towards the restroom to clear your confusion, and as you entered you were greeted by Peter's reflection instead of yours. You two had switched bodies.